# LintCode

**Repository Path**: ouyangpengdev/LintCode

## Basic Information

- **Project Name**: LintCode
- **Description**: Java Solutions to problems on LintCode/LeetCode
- **Primary Language**: Java
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2021-03-23
- **Last Updated**: 2021-03-23

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Java Algorithm Problems

### 程序员的一天
从开始这个Github已经有将近两年时间, 很高兴这个repo可以帮到有需要的人. 我一直认为, 知识本身是无价的, 因此每逢闲暇, 我就会来维护这个repo, 给刷题的朋友们一些我的想法和见解. 下面来简单介绍一下这个repo:

**README.md**: 所有所做过的题目

**ReviewPage.md**: 所有题目的总结和归纳（不断完善中）

**KnowledgeHash2.md**: 对所做过的知识点的一些笔记

**SystemDesign.md**: 对系统设计的一些笔记

**Future Milestone**: 我准备将一些有意思的题目，做成视频的形式给大家参考

希望大家学习顺利, 对未来充满希望(程序员也是找到好老板的!)
有问题可以给我写邮件(wangdeve@gmail.com), 或者在GitHub上发issue给我.

| Squence | Problem       | Level  | Language  | Tags | Video Tutorial|
|:-------:|:--------------|:------:|:---------:|:----:|:-------------:|
|0|[Count of Smaller Number before itself.java](https://github.com/awangdev/LintCode/blob/master/Java/Count%20of%20Smaller%20Number%20before%20itself.java)|Hard|Java|[]||
|1|[Evaluate Division.java](https://github.com/awangdev/LintCode/blob/master/Java/Evaluate%20Division.java)|Medium|Java|[BFS, DFS, Graph, Union Find]||
|2|[Fraction to Recurring Decimal.java](https://github.com/awangdev/LintCode/blob/master/Java/Fraction%20to%20Recurring%20Decimal.java)|Medium|Java|[Hash Table, Math]||
|3|[Gray Code.java](https://github.com/awangdev/LintCode/blob/master/Java/Gray%20Code.java)|Medium|Java|[Backtracking]||
|4|[Hamming Distance.java](https://github.com/awangdev/LintCode/blob/master/Java/Hamming%20Distance.java)|Easy|Java|[]||
|5|[Happy Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Happy%20Number.java)|Easy|Java|[]||
|6|[HashWithArray.java](https://github.com/awangdev/LintCode/blob/master/Java/HashWithArray.java)|Easy|Java|[]||
|7|[Heaters.java](https://github.com/awangdev/LintCode/blob/master/Java/Heaters.java)|Easy|Java|[]||
|8|[IndexMatch.java](https://github.com/awangdev/LintCode/blob/master/Java/IndexMatch.java)|Easy|Java|[]||
|9|[Insert Node in a Binary Search Tree .java](https://github.com/awangdev/LintCode/blob/master/Java/Insert%20Node%20in%20a%20Binary%20Search%20Tree%20.java)|Easy|Java|[BST]||
|10|[Jewels and Stones.java](https://github.com/awangdev/LintCode/blob/master/Java/Jewels%20and%20Stones.java)|Easy|Java|[Hash Table]||
|11|[Kth Smallest Sum In Two Sorted Arrays.java](https://github.com/awangdev/LintCode/blob/master/Java/Kth%20Smallest%20Sum%20In%20Two%20Sorted%20Arrays.java)|Hard|Java|[]||
|12|[LFU Cache.java](https://github.com/awangdev/LintCode/blob/master/Java/LFU%20Cache.java)|Hard|Java|[Design, Hash Table]||
|13|[Longest Univalue Path.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Univalue%20Path.java)|Easy|Java|[]||
|14|[Majority Number II.java](https://github.com/awangdev/LintCode/blob/master/Java/Majority%20Number%20II.java)|Medium|Java|[Enumeration, Greedy]||
|15|[Majority Number III.java](https://github.com/awangdev/LintCode/blob/master/Java/Majority%20Number%20III.java)|Medium|Java|[Hash Table, Linked List]||
|16|[Matrix Zigzag Traversal.java](https://github.com/awangdev/LintCode/blob/master/Java/Matrix%20Zigzag%20Traversal.java)|Easy|Java|[]||
|17|[Maximum Subarray III.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximum%20Subarray%20III.java)|Review|Java|[]||
|18|[Minimum Absolute Difference in BST.java](https://github.com/awangdev/LintCode/blob/master/Java/Minimum%20Absolute%20Difference%20in%20BST.java)|Easy|Java|[BST]||
|19|[Minimum Height Trees.java](https://github.com/awangdev/LintCode/blob/master/Java/Minimum%20Height%20Trees.java)|Medium|Java|[BFS, Graph]||
|20|[Missing Ranges.java](https://github.com/awangdev/LintCode/blob/master/Java/Missing%20Ranges.java)|Medium|Java|[Array]||
|21|[Next Permutation.java](https://github.com/awangdev/LintCode/blob/master/Java/Next%20Permutation.java)|Medium|Java|[Array]||
|22|[O(1) Check Power of 2.java](https://github.com/awangdev/LintCode/blob/master/Java/O(1)%20Check%20Power%20of%202.java)|Easy|Java|[Bit Manipulation]||
|23|[Palindrome Permutation II.java](https://github.com/awangdev/LintCode/blob/master/Java/Palindrome%20Permutation%20II.java)|Medium|Java|[Backtracking, Permutation]||
|24|[Partition Array by Odd and Even.java](https://github.com/awangdev/LintCode/blob/master/Java/Partition%20Array%20by%20Odd%20and%20Even.java)|Easy|Java|[Array, Two Pointers]||
|25|[Pascal's Triangle II.java](https://github.com/awangdev/LintCode/blob/master/Java/Pascal's%20Triangle%20II.java)|Easy|Java|[]||
|26|[Permutation Index.java](https://github.com/awangdev/LintCode/blob/master/Java/Permutation%20Index.java)|Easy|Java|[]||
|27|[Permutation Sequence.java](https://github.com/awangdev/LintCode/blob/master/Java/Permutation%20Sequence.java)|Medium|Java|[Backtracking, Math]||
|28|[Prefix and Suffix Search.java](https://github.com/awangdev/LintCode/blob/master/Java/Prefix%20and%20Suffix%20Search.java)|Hard|Java|[Trie]||
|29|[Product of Array Exclude Itself.java](https://github.com/awangdev/LintCode/blob/master/Java/Product%20of%20Array%20Exclude%20Itself.java)|Medium|Java|[Array]||
|30|[Recover Rotated Sorted Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Recover%20Rotated%20Sorted%20Array.java)|Easy|Java|[Array]||
|31|[Remove Duplicates from Unsorted List.java](https://github.com/awangdev/LintCode/blob/master/Java/Remove%20Duplicates%20from%20Unsorted%20List.java)|Medium|Java|[Linked List]||
|32|[Remove Node in Binary Search Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Remove%20Node%20in%20Binary%20Search%20Tree.java)|Hard|Java|[BST]||
|33|[Reshape the Matrix.java](https://github.com/awangdev/LintCode/blob/master/Java/Reshape%20the%20Matrix.java)|Easy|Java|[]||
|34|[Reverse String.java](https://github.com/awangdev/LintCode/blob/master/Java/Reverse%20String.java)|Easy|Java|[]||
|35|[Rotate Image.java](https://github.com/awangdev/LintCode/blob/master/Java/Rotate%20Image.java)|Medium|Java|[Array, Enumeration]||
|36|[Search in Rotated Sorted Array II.java](https://github.com/awangdev/LintCode/blob/master/Java/Search%20in%20Rotated%20Sorted%20Array%20II.java)|Medium|Java|[Array, Binary Search]||
|37|[Search Insert Position.java](https://github.com/awangdev/LintCode/blob/master/Java/Search%20Insert%20Position.java)|Easy|Java|[]||
|38|[Shortest Word Distance.java](https://github.com/awangdev/LintCode/blob/master/Java/Shortest%20Word%20Distance.java)|Easy|Java|[]||
|39|[Single Number II.java](https://github.com/awangdev/LintCode/blob/master/Java/Single%20Number%20II.java)|Medium|Java|[Bit Manipulation]||
|40|[Single Number III.java](https://github.com/awangdev/LintCode/blob/master/Java/Single%20Number%20III.java)|Medium|Java|[Bit Manipulation]||
|41|[Single Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Single%20Number.java)|Easy|Java|[]||
|42|[Space Replacement.java](https://github.com/awangdev/LintCode/blob/master/Java/Space%20Replacement.java)|Medium|Java|[String]||
|43|[Stone Game.java](https://github.com/awangdev/LintCode/blob/master/Java/Stone%20Game.java)|Medium|Java|[DP]||
|44|[String Permutation.java](https://github.com/awangdev/LintCode/blob/master/Java/String%20Permutation.java)|Easy|Java|[]||
|45|[Subarray Sum II.java](https://github.com/awangdev/LintCode/blob/master/Java/Subarray%20Sum%20II.java)|Hard|Java|[Array, Binary Search, Two Pointers]||
|46|[The Smallest Difference.java](https://github.com/awangdev/LintCode/blob/master/Java/The%20Smallest%20Difference.java)|Medium|Java|[Array, Sort, Two Pointers]||
|47|[Total Occurrence of Target.java](https://github.com/awangdev/LintCode/blob/master/Java/Total%20Occurrence%20of%20Target.java)|Medium|Java|[]||
|48|[Trailing Zeros.java](https://github.com/awangdev/LintCode/blob/master/Java/Trailing%20Zeros.java)|Easy|Java|[Math]||
|49|[Two Lists Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Two%20Lists%20Sum.java)|Medium|Java|[Linked List]||
|50|[Two Strings Are Anagrams.java](https://github.com/awangdev/LintCode/blob/master/Java/Two%20Strings%20Are%20Anagrams.java)|Easy|Java|[]||
|51|[Valid Sudoku.java](https://github.com/awangdev/LintCode/blob/master/Java/Valid%20Sudoku.java)|Easy|Java|[Enumeration, Hash Table]||
|52|[Word Pattern.java](https://github.com/awangdev/LintCode/blob/master/Java/Word%20Pattern.java)|Easy|Java|[]||
|53|[Zigzag Iterator.java](https://github.com/awangdev/LintCode/blob/master/Java/Zigzag%20Iterator.java)|Medium|Java|[BST]||
|54|[Find Anagram Mappings.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20Anagram%20Mappings.java)|Easy|Java|[Hash Table]||
|55|[Judge Route Circle.java](https://github.com/awangdev/LintCode/blob/master/Java/Judge%20Route%20Circle.java)|Easy|Java|[String]||
|56|[Island Perimeter.java](https://github.com/awangdev/LintCode/blob/master/Java/Island%20Perimeter.java)|Easy|Java|[Hash Table]||
|57|[Power of Three.java](https://github.com/awangdev/LintCode/blob/master/Java/Power%20of%20Three.java)|Easy|Java|[Math]||
|58|[Plus One.java](https://github.com/awangdev/LintCode/blob/master/Java/Plus%20One.java)|Easy|Java|[Array, Math]||
|59|[Power of Two.java](https://github.com/awangdev/LintCode/blob/master/Java/Power%20of%20Two.java)|Easy|Java|[Bit Manipulation, Math]||
|60|[Reverse Vowels of a String.java](https://github.com/awangdev/LintCode/blob/master/Java/Reverse%20Vowels%20of%20a%20String.java)|Easy|Java|[String, Two Pointers]||
|61|[Guess Number Higher or Lower.java](https://github.com/awangdev/LintCode/blob/master/Java/Guess%20Number%20Higher%20or%20Lower.java)|Easy|Java|[Binary Search]||
|62|[Encode and Decode TinyURL.java](https://github.com/awangdev/LintCode/blob/master/Java/Encode%20and%20Decode%20TinyURL.java)|Medium|Java|[Hash Table, Math]||
|63|[Wiggle Sort.java](https://github.com/awangdev/LintCode/blob/master/Java/Wiggle%20Sort.java)|Medium|Java|[Array, Sort]||
|64|[Queue Reconstruction by Height.java](https://github.com/awangdev/LintCode/blob/master/Java/Queue%20Reconstruction%20by%20Height.java)|Medium|Java|[Greedy]||
|65|[Two Sum II - Input array is sorted.java](https://github.com/awangdev/LintCode/blob/master/Java/Two%20Sum%20II%20-%20Input%20array%20is%20sorted.java)|Medium|Java|[Array, Binary Search, Two Pointers]||
|66|[2 Sum II.java](https://github.com/awangdev/LintCode/blob/master/Java/2%20Sum%20II.java)|Medium|Java|[Array, Binary Search, Two Pointers]||
|67|[Coin Change.java](https://github.com/awangdev/LintCode/blob/master/Java/Coin%20Change.java)|Medium|Java|[Backpack DP, DP, Memoization]||
|68|[Maximum Product Subarray.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximum%20Product%20Subarray.java)|Medium|Java|[Array, DP, Subarray]||
|69|[3 Sum Closest.java](https://github.com/awangdev/LintCode/blob/master/Java/3%20Sum%20Closest.java)|Medium|Java|[Array, Two Pointers]||
|70|[Triangle Count.java](https://github.com/awangdev/LintCode/blob/master/Java/Triangle%20Count.java)|Medium|Java|[Array]||
|71|[3Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/3Sum.java)|Medium|Java|[Array, Two Pointers]||
|72|[k Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/k%20Sum.java)|Hard|Java|[DP]||
|73|[Unique Binary Search Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Unique%20Binary%20Search%20Tree.java)|Medium|Java|[BST, DP, Tree]||
|74|[Trim a Binary Search Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Trim%20a%20Binary%20Search%20Tree.java)|Easy|Java|[BST, Tree]||
|75|[Unique Paths II.java](https://github.com/awangdev/LintCode/blob/master/Java/Unique%20Paths%20II.java)|Medium|Java|[Array, Coordinate DP, DP]||
|76|[Bomb Enemy.java](https://github.com/awangdev/LintCode/blob/master/Java/Bomb%20Enemy.java)|Medium|Java|[Coordinate DP, DP]||
|77|[3Sum Smaller.java](https://github.com/awangdev/LintCode/blob/master/Java/3Sum%20Smaller.java)|Medium|Java|[Array, Two Pointers]||
|78|[Array Partition I.java](https://github.com/awangdev/LintCode/blob/master/Java/Array%20Partition%20I.java)|Easy|Java|[Array]||
|79|[1-bit and 2-bit Characters.java](https://github.com/awangdev/LintCode/blob/master/Java/1-bit%20and%202-bit%20Characters.java)|Easy|Java|[Array]||
|80|[Non-decreasing Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Non-decreasing%20Array.java)|Easy|Java|[Array]||
|81|[Max Consecutive Ones.java](https://github.com/awangdev/LintCode/blob/master/Java/Max%20Consecutive%20Ones.java)|Easy|Java|[Array]||
|82|[Find All Numbers Disappeared in an Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20All%20Numbers%20Disappeared%20in%20an%20Array.java)|Easy|Java|[Array]||
|83|[Maximum Average Subarray I.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximum%20Average%20Subarray%20I.java)|Easy|Java|[Array, Subarray]||
|84|[Largest Number At Least Twice of Others.java](https://github.com/awangdev/LintCode/blob/master/Java/Largest%20Number%20At%20Least%20Twice%20of%20Others.java)|Easy|Java|[Array]||
|85|[Toeplitz Matrix.java](https://github.com/awangdev/LintCode/blob/master/Java/Toeplitz%20Matrix.java)|Easy|Java|[Array]||
|86|[Sum of Two Integers.java](https://github.com/awangdev/LintCode/blob/master/Java/Sum%20of%20Two%20Integers.java)|Easy|Java|[Bit Manipulation]||
|87|[Swap Bits.java](https://github.com/awangdev/LintCode/blob/master/Java/Swap%20Bits.java)|Easy|Java|[Bit Manipulation]||
|88|[Update Bits.java](https://github.com/awangdev/LintCode/blob/master/Java/Update%20Bits.java)|Medium|Java|[Bit Manipulation]||
|89|[Maximum XOR of Two Numbers in an Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximum%20XOR%20of%20Two%20Numbers%20in%20an%20Array.java)|Medium|Java|[Bit Manipulation, Trie]||
|90|[Perfect Squares.java](https://github.com/awangdev/LintCode/blob/master/Java/Perfect%20Squares.java)|Medium|Java|[BFS, DP, Math, Partition DP]||
|91|[Backpack VI.java](https://github.com/awangdev/LintCode/blob/master/Java/Backpack%20VI.java)|Medium|Java|[Backpack DP, DP]||
|92|[Copy Books.java](https://github.com/awangdev/LintCode/blob/master/Java/Copy%20Books.java)|Hard|Java|[Binary Search, DP, Partition DP]||
|93|[Valid Perfect Square.java](https://github.com/awangdev/LintCode/blob/master/Java/Valid%20Perfect%20Square.java)|Review|Java|[Binary Search, Math]||
|94|[Intersection of Two Arrays II.java](https://github.com/awangdev/LintCode/blob/master/Java/Intersection%20of%20Two%20Arrays%20II.java)|Easy|Java|[Binary Search, Hash Table, Sort, Two Pointers]||
|95|[Scramble String.java](https://github.com/awangdev/LintCode/blob/master/Java/Scramble%20String.java)|Hard|Java|[DP, Interval DP, String]||
|96|[Binary Search Tree Iterator.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Search%20Tree%20Iterator.java)|Medium|Java|[BST, Design, Stack, Tree]||
|97|[Flatten Nested List Iterator.java](https://github.com/awangdev/LintCode/blob/master/Java/Flatten%20Nested%20List%20Iterator.java)|Medium|Java|[Design, Stack]||
|98|[Best Time to Buy and Sell Stock with Cooldown.java](https://github.com/awangdev/LintCode/blob/master/Java/Best%20Time%20to%20Buy%20and%20Sell%20Stock%20with%20Cooldown.java)|Medium|Java|[DP]||
|99|[Find Peak Element.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20Peak%20Element.java)|Medium|Java|[Array, Binary Search]||
|100|[Longest Common Subsequence.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Common%20Subsequence.java)|Medium|Java|[DP, Double Sequence DP, Sequence DP]||
|101|[Interleaving String.java](https://github.com/awangdev/LintCode/blob/master/Java/Interleaving%20String.java)|Hard|Java|[DP, String]||
|102|[Letter Combinations of a Phone Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Letter%20Combinations%20of%20a%20Phone%20Number.java)|Medium|Java|[Backtracking, String]||
|103|[Edit Distance.java](https://github.com/awangdev/LintCode/blob/master/Java/Edit%20Distance.java)|Hard|Java|[DP, Double Sequence DP, Sequence DP, String]||
|104|[Distinct Subsequences.java](https://github.com/awangdev/LintCode/blob/master/Java/Distinct%20Subsequences.java)|Hard|Java|[DP, String]||
|105|[Majority Element.java](https://github.com/awangdev/LintCode/blob/master/Java/Majority%20Element.java)|Easy|Java|[Array, Bit Manipulation, Divide and Conquer]||
|106|[Ones and Zeroes.java](https://github.com/awangdev/LintCode/blob/master/Java/Ones%20and%20Zeroes.java)|Hard|Java|[DP]||
|107|[Pow(x, n).java](https://github.com/awangdev/LintCode/blob/master/Java/Pow(x,%20n).java)|Medium|Java|[Binary Search, Math]||
|108|[Word Break II.java](https://github.com/awangdev/LintCode/blob/master/Java/Word%20Break%20II.java)|Hard|Java|[Backtracking, DFS, DP, Hash Table, Memoization]||
|109|[Nested List Weight Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Nested%20List%20Weight%20Sum.java)|Easy|Java|[BFS, DFS]||
|110|[Same Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Same%20Tree.java)|Easy|Java|[DFS, Tree]||
|111|[Convert Sorted Array to Binary Search Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Convert%20Sorted%20Array%20to%20Binary%20Search%20Tree.java)|Easy|Java|[DFS, Divide and Conquer, Tree]||
|112|[Construct Binary Tree from Preorder and Inorder Traversal.java](https://github.com/awangdev/LintCode/blob/master/Java/Construct%20Binary%20Tree%20from%20Preorder%20and%20Inorder%20Traversal.java)|Medium|Java|[Array, DFS, Divide and Conquer, Hash Table, Tree]||
|113|[Add Digits.java](https://github.com/awangdev/LintCode/blob/master/Java/Add%20Digits.java)|Easy|Java|[Math]||
|114|[Add Two Numbers.java](https://github.com/awangdev/LintCode/blob/master/Java/Add%20Two%20Numbers.java)|Medium|Java|[Linked List, Math]||
|115|[Add Two Numbers II.java](https://github.com/awangdev/LintCode/blob/master/Java/Add%20Two%20Numbers%20II.java)|Medium|Java|[Linked List]||
|116|[Balanced Binary Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Balanced%20Binary%20Tree.java)|Medium|Java|[DFS, Tree]||
|117|[Valid Anagram.java](https://github.com/awangdev/LintCode/blob/master/Java/Valid%20Anagram.java)|Easy|Java|[Hash Table, Sort]||
|118|[Populating Next Right Pointers in Each Node.java](https://github.com/awangdev/LintCode/blob/master/Java/Populating%20Next%20Right%20Pointers%20in%20Each%20Node.java)|Medium|Java|[DFS, Divide and Conquer, Tree]||
|119|[Validate Binary Search Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Validate%20Binary%20Search%20Tree.java)|Medium|Java|[BST, DFS, Divide and Conquer, Tree]||
|120|[Convert Sorted List to Binary Search Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Convert%20Sorted%20List%20to%20Binary%20Search%20Tree.java)|Medium|Java|[BST, DFS, Divide and Conquer, Linked List]||
|121|[Flatten Binary Tree to Linked List.java](https://github.com/awangdev/LintCode/blob/master/Java/Flatten%20Binary%20Tree%20to%20Linked%20List.java)|Medium|Java|[Binary Tree, DFS]||
|122|[Binary Tree Paths.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Paths.java)|Easy|Java|[Backtracking, Binary Tree, DFS]||
|123|[Minimum Size Subarray Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Minimum%20Size%20Subarray%20Sum.java)|Medium|Java|[Array, Binary Search, Subarray, Two Pointers]||
|124|[Longest Substring Without Repeating Characters.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Substring%20Without%20Repeating%20Characters.java)|Medium|Java|[Hash Table, String, Two Pointers]||
|125|[Minimum Window Substring.java](https://github.com/awangdev/LintCode/blob/master/Java/Minimum%20Window%20Substring.java)|Hard|Java|[Hash Table, String, Two Pointers]||
|126|[Linked List Cycle.java](https://github.com/awangdev/LintCode/blob/master/Java/Linked%20List%20Cycle.java)|Easy|Java|[Linked List, Two Pointers]||
|127|[Remove Nth Node From End of List.java](https://github.com/awangdev/LintCode/blob/master/Java/Remove%20Nth%20Node%20From%20End%20of%20List.java)|Medium|Java|[Linked List, Two Pointers]||
|128|[Longest Substring with At Most K Distinct Characters.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Substring%20with%20At%20Most%20K%20Distinct%20Characters.java)|Hard|Java|[Hash Table, Sliding Window, String]||
|129|[Linked List Cycle II.java](https://github.com/awangdev/LintCode/blob/master/Java/Linked%20List%20Cycle%20II.java)|Medium|Java|[Linked List, Math, Two Pointers]||
|130|[Kth Smallest Element in a Sorted Matrix.java](https://github.com/awangdev/LintCode/blob/master/Java/Kth%20Smallest%20Element%20in%20a%20Sorted%20Matrix.java)|Medium|Java|[Binary Search, Heap]||
|131|[Find Minimum in Rotated Sorted Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20Minimum%20in%20Rotated%20Sorted%20Array.java)|Medium|Java|[Array, Binary Search]||
|132|[Find Minimum in Rotated Sorted Array II.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20Minimum%20in%20Rotated%20Sorted%20Array%20II.java)|Hard|Java|[Array, Binary Search]||
|133|[Connecting Graph.java](https://github.com/awangdev/LintCode/blob/master/Java/Connecting%20Graph.java)|Medium|Java|[Union Find]||
|134|[Connecting Graph II.java](https://github.com/awangdev/LintCode/blob/master/Java/Connecting%20Graph%20II.java)|Medium|Java|[Union Find]||
|135|[Connecting Graph III.java](https://github.com/awangdev/LintCode/blob/master/Java/Connecting%20Graph%20III.java)|Medium|Java|[Union Find]||
|136|[Number of Islands.java](https://github.com/awangdev/LintCode/blob/master/Java/Number%20of%20Islands.java)|Medium|Java|[BFS, DFS, Matrix DFS, Union Find]||
|137|[Number of Islands II.java](https://github.com/awangdev/LintCode/blob/master/Java/Number%20of%20Islands%20II.java)|Hard|Java|[Union Find]||
|138|[Surrounded Regions.java](https://github.com/awangdev/LintCode/blob/master/Java/Surrounded%20Regions.java)|Medium|Java|[BFS, DFS, Matrix DFS, Union Find]||
|139|[Implement Trie (Prefix Tree).java](https://github.com/awangdev/LintCode/blob/master/Java/Implement%20Trie%20(Prefix%20Tree).java)|Medium|Java|[Design, Trie]||
|140|[Add and Search Word - Data structure design.java](https://github.com/awangdev/LintCode/blob/master/Java/Add%20and%20Search%20Word%20-%20Data%20structure%20design.java)|Medium|Java|[Backtracking, Design, Trie]||
|141|[Word Search II.java](https://github.com/awangdev/LintCode/blob/master/Java/Word%20Search%20II.java)|Hard|Java|[Backtracking, DFS, Trie]||
|142|[Word Search.java](https://github.com/awangdev/LintCode/blob/master/Java/Word%20Search.java)|Medium|Java|[Array, Backtracking, DFS]||
|143|[Word Squares.java](https://github.com/awangdev/LintCode/blob/master/Java/Word%20Squares.java)|Hard|Java|[Backtracking, Trie]||
|144|[Trapping Rain Water.java](https://github.com/awangdev/LintCode/blob/master/Java/Trapping%20Rain%20Water.java)|Hard|Java|[Array, Stack, Two Pointers]||
|145|[Min Stack.java](https://github.com/awangdev/LintCode/blob/master/Java/Min%20Stack.java)|Easy|Java|[Design, Stack]||
|146|[Implement Queue using Stacks.java](https://github.com/awangdev/LintCode/blob/master/Java/Implement%20Queue%20using%20Stacks.java)|Easy|Java|[Design, Stack]||
|147|[Decode String.java](https://github.com/awangdev/LintCode/blob/master/Java/Decode%20String.java)|Medium|Java|[DFS, Divide and Conquer, Stack]||
|148|[Largest Rectangle in Histogram.java](https://github.com/awangdev/LintCode/blob/master/Java/Largest%20Rectangle%20in%20Histogram.java)|Hard|Java|[Array, Monotonous Stack, Stack]||
|149|[Maximum Binary Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximum%20Binary%20Tree.java)|Medium|Java|[Stack, Tree]||
|150|[Reverse Integer.java](https://github.com/awangdev/LintCode/blob/master/Java/Reverse%20Integer.java)|Easy|Java|[Math]||
|151|[Swap Nodes in Pairs.java](https://github.com/awangdev/LintCode/blob/master/Java/Swap%20Nodes%20in%20Pairs.java)|Medium|Java|[Linked List]||
|152|[Find Peak Element II.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20Peak%20Element%20II.java)|Hard|Java|[Binary Search, DFS, Divide and Conquer]||
|153|[Sqrt(x).java](https://github.com/awangdev/LintCode/blob/master/Java/Sqrt(x).java)|Easy|Java|[Binary Search, Math]||
|154|[First Bad Version.java](https://github.com/awangdev/LintCode/blob/master/Java/First%20Bad%20Version.java)|Easy|Java|[Binary Search]||
|155|[Wood Cut.java](https://github.com/awangdev/LintCode/blob/master/Java/Wood%20Cut.java)|Medium|Java|[Binary Search]||
|156|[Find the Duplicate Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20the%20Duplicate%20Number.java)|Medium|Java|[Array, Binary Search, Two Pointers]||
|157|[Palindrome Pairs.java](https://github.com/awangdev/LintCode/blob/master/Java/Palindrome%20Pairs.java)|Hard|Java|[Hash Table, String, Trie]||
|158|[Game of Life.java](https://github.com/awangdev/LintCode/blob/master/Java/Game%20of%20Life.java)|Medium|Java|[Array]||
|159|[Maximum Average Subarray II.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximum%20Average%20Subarray%20II.java)|Review|Java|[Array, Binary Search, PreSum]||
|160|[Meeting Rooms.java](https://github.com/awangdev/LintCode/blob/master/Java/Meeting%20Rooms.java)|Easy|Java|[PriorityQueue, Sort, Sweep Line]||
|161|[Number of Airplane in the sky.java](https://github.com/awangdev/LintCode/blob/master/Java/Number%20of%20Airplane%20in%20the%20sky.java)|Medium|Java|[Array, Interval, PriorityQueue, Sort, Sweep Line]||
|162|[Meeting Rooms II.java](https://github.com/awangdev/LintCode/blob/master/Java/Meeting%20Rooms%20II.java)|Medium|Java|[Greedy, Heap, PriorityQueue, Sort, Sweep Line]||
|163|[The Skyline Problem.java](https://github.com/awangdev/LintCode/blob/master/Java/The%20Skyline%20Problem.java)|Review|Java|[Binary Indexed Tree, Divide and Conquer, Heap, PriorityQueue, Segment Tree, Sweep Line]||
|164|[Unique Path.java](https://github.com/awangdev/LintCode/blob/master/Java/Unique%20Path.java)|Medium|Java|[Array, Coordinate DP, DP]||
|165|[Maximal Rectangle.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximal%20Rectangle.java)|Hard|Java|[Array, DP, Hash Table, Stack]||
|166|[Maximal Square.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximal%20Square.java)|Medium|Java|[Coordinate DP, DP]||
|167|[Longest Increasing Path in a Matrix.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Increasing%20Path%20in%20a%20Matrix.java)|Hard|Java|[Coordinate DP, DFS, DP, Memoization, Topological Sort]||
|168|[Coins in a Line.java](https://github.com/awangdev/LintCode/blob/master/Java/Coins%20in%20a%20Line.java)|Medium|Java|[DP, Game Theory, Greedy]||
|169|[Coins in a Line II.java](https://github.com/awangdev/LintCode/blob/master/Java/Coins%20in%20a%20Line%20II.java)|Medium|Java|[Array, DP, Game Theory, Memoization, MiniMax]||
|170|[Binary Tree Inorder Traversal.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Inorder%20Traversal.java)|Easy|Java|[Hash Table, Stack, Tree]||
|171|[Binary Tree Postorder Traversal.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Postorder%20Traversal.java)|Medium|Java|[Stack, Tree, Two Stacks]||
|172|[Change to Anagram.java](https://github.com/awangdev/LintCode/blob/master/Java/Change%20to%20Anagram.java)|Easy|Java|[String]||
|173|[Classical Binary Search.java](https://github.com/awangdev/LintCode/blob/master/Java/Classical%20Binary%20Search.java)|Easy|Java|[Binary Search]||
|174|[Climbing Stairs.java](https://github.com/awangdev/LintCode/blob/master/Java/Climbing%20Stairs.java)|Easy|Java|[DP, Memoization, Sequence DP]||
|175|[Coins in a Line III.java](https://github.com/awangdev/LintCode/blob/master/Java/Coins%20in%20a%20Line%20III.java)|Hard|Java|[Array, DP, Game Theory, Interval DP, Memoization]||
|176|[Closest Binary Search Tree Value.java](https://github.com/awangdev/LintCode/blob/master/Java/Closest%20Binary%20Search%20Tree%20Value.java)|Easy|Java|[BST, Binary Search, Tree]||
|177|[Compare Version Numbers.java](https://github.com/awangdev/LintCode/blob/master/Java/Compare%20Version%20Numbers.java)|Medium|Java|[String]||
|178|[Count Complete Tree Nodes.java](https://github.com/awangdev/LintCode/blob/master/Java/Count%20Complete%20Tree%20Nodes.java)|Medium|Java|[Binary Search, Tree]||
|179|[Course Schedule.java](https://github.com/awangdev/LintCode/blob/master/Java/Course%20Schedule.java)|Medium|Java|[BFS, Backtracking, DFS, Graph, Topological Sort]||
|180|[Course Schedule II.java](https://github.com/awangdev/LintCode/blob/master/Java/Course%20Schedule%20II.java)|Medium|Java|[BFS, DFS, Graph, Topological Sort]||
|181|[Binary Tree Preorder Traversal.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Preorder%20Traversal.java)|Easy|Java|[BFS, DFS, Stack, Tree]||
|182|[Closest Number in Sorted Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Closest%20Number%20in%20Sorted%20Array.java)|Easy|Java|[Binary Search]||
|183|[Complete Binary Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Complete%20Binary%20Tree.java)|Easy|Java|[BFS, Tree]||
|184|[Compare Strings.java](https://github.com/awangdev/LintCode/blob/master/Java/Compare%20Strings.java)|Easy|Java|[String]||
|185|[Contains Duplicate.java](https://github.com/awangdev/LintCode/blob/master/Java/Contains%20Duplicate.java)|Easy|Java|[Array, Hash Table]||
|186|[Contains Duplicate II.java](https://github.com/awangdev/LintCode/blob/master/Java/Contains%20Duplicate%20II.java)|Easy|Java|[Array, Hash Table]||
|187|[Contains Duplicate III.java](https://github.com/awangdev/LintCode/blob/master/Java/Contains%20Duplicate%20III.java)|Medium|Java|[BST]||
|188|[Burst Balloons.java](https://github.com/awangdev/LintCode/blob/master/Java/Burst%20Balloons.java)|Hard|Java|[DP, Divide and Conquer, Interval DP, Memoization]||
|189|[Nim Game.java](https://github.com/awangdev/LintCode/blob/master/Java/Nim%20Game.java)|Easy|Java|[Brainteaser, DP, Game Theory]||
|190|[Convert Integer A to Integer B.java](https://github.com/awangdev/LintCode/blob/master/Java/Convert%20Integer%20A%20to%20Integer%20B.java)|Easy|Java|[Bit Manipulation]||
|191|[Cosine Similarity.java](https://github.com/awangdev/LintCode/blob/master/Java/Cosine%20Similarity.java)|Easy|Java|[Basic Implementation]||
|192|[Count 1 in Binary.java](https://github.com/awangdev/LintCode/blob/master/Java/Count%201%20in%20Binary.java)|Easy|Java|[Bit Manipulation]||
|193|[Count and Say.java](https://github.com/awangdev/LintCode/blob/master/Java/Count%20and%20Say.java)|Easy|Java|[Basic Implementation, String]||
|194|[K Edit Distance.java](https://github.com/awangdev/LintCode/blob/master/Java/K%20Edit%20Distance.java)|Hard|Java|[DP, Double Sequence DP, Sequence DP, Trie]||
|195|[Jump Game.java](https://github.com/awangdev/LintCode/blob/master/Java/Jump%20Game.java)|Medium|Java|[Array, DP, Greedy]||
|196|[Coin Change 2.java](https://github.com/awangdev/LintCode/blob/master/Java/Coin%20Change%202.java)|Medium|Java|[Backpack DP, DP]||
|197|[Paint House.java](https://github.com/awangdev/LintCode/blob/master/Java/Paint%20House.java)|Easy|Java|[DP, Sequence DP, Status DP]||
|198|[Decode Ways.java](https://github.com/awangdev/LintCode/blob/master/Java/Decode%20Ways.java)|Medium|Java|[DP, Partition DP, String]||
|199|[Longest Continuous Increasing Subsequence.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Continuous%20Increasing%20Subsequence.java)|Easy|Java|[Array, Coordinate DP, DP]||
|200|[Minimum Path Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Minimum%20Path%20Sum.java)|Medium|Java|[Array, Coordinate DP, DP]||
|201|[Counting Bits.java](https://github.com/awangdev/LintCode/blob/master/Java/Counting%20Bits.java)|Medium|Java|[Bit Manipulation, Bitwise DP, DP]||
|202|[Continuous Subarray Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Continuous%20Subarray%20Sum.java)|Medium|Java|[Coordinate DP, DP, Math, Subarray]||
|203|[House Robber.java](https://github.com/awangdev/LintCode/blob/master/Java/House%20Robber.java)|Easy|Java|[DP, Sequence DP]||
|204|[House Robber II.java](https://github.com/awangdev/LintCode/blob/master/Java/House%20Robber%20II.java)|Medium|Java|[DP, Sequence DP, Status DP]||
|205|[House Robber III.java](https://github.com/awangdev/LintCode/blob/master/Java/House%20Robber%20III.java)|Medium|Java|[DFS, DP, Status DP, Tree]||
|206|[Paint House II.java](https://github.com/awangdev/LintCode/blob/master/Java/Paint%20House%20II.java)|Hard|Java|[DP, Sequence DP, Status DP]||
|207|[Best Time to Buy and Sell Stock III.java](https://github.com/awangdev/LintCode/blob/master/Java/Best%20Time%20to%20Buy%20and%20Sell%20Stock%20III.java)|Hard|Java|[Array, DP, Sequence DP]||
|208|[Best Time to Buy and Sell Stock IV.java](https://github.com/awangdev/LintCode/blob/master/Java/Best%20Time%20to%20Buy%20and%20Sell%20Stock%20IV.java)|Hard|Java|[DP, Sequence DP]||
|209|[Russian Doll Envelopes.java](https://github.com/awangdev/LintCode/blob/master/Java/Russian%20Doll%20Envelopes.java)|Hard|Java|[Binary Search, Coordinate DP, DP]||
|210|[Permutation in String.java](https://github.com/awangdev/LintCode/blob/master/Java/Permutation%20in%20String.java)|Medium|Java|[Two Pointers]||
|211|[Permutations II.java](https://github.com/awangdev/LintCode/blob/master/Java/Permutations%20II.java)|Medium|Java|[Backtracking]||
|212|[Shuffle an Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Shuffle%20an%20Array.java)|Medium|Java|[Permutation]||
|213|[Find All Anagrams in a String.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20All%20Anagrams%20in%20a%20String.java)|Easy|Java|[Hash Table, Sliding Window]||
|214|[Group Anagrams.java](https://github.com/awangdev/LintCode/blob/master/Java/Group%20Anagrams.java)|Medium|Java|[Hash Table, String]||
|215|[Backpack.java](https://github.com/awangdev/LintCode/blob/master/Java/Backpack.java)|Medium|Java|[Backpack DP, DP]||
|216|[Backpack II.java](https://github.com/awangdev/LintCode/blob/master/Java/Backpack%20II.java)|Medium|Java|[Backpack DP, DP]||
|217|[Backpack V.java](https://github.com/awangdev/LintCode/blob/master/Java/Backpack%20V.java)|Medium|Java|[Backpack DP, DP]||
|218|[Count Primes.java](https://github.com/awangdev/LintCode/blob/master/Java/Count%20Primes.java)|Easy|Java|[Hash Table, Math]||
|219|[Delete Node in a Linked List.java](https://github.com/awangdev/LintCode/blob/master/Java/Delete%20Node%20in%20a%20Linked%20List.java)|Easy|Java|[Linked List]||
|220|[Excel Sheet Column Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Excel%20Sheet%20Column%20Number.java)|Easy|Java|[Math]||
|221|[Excel Sheet Column Title.java](https://github.com/awangdev/LintCode/blob/master/Java/Excel%20Sheet%20Column%20Title.java)|Easy|Java|[Math]||
|222|[Flip Game.java](https://github.com/awangdev/LintCode/blob/master/Java/Flip%20Game.java)|Easy|Java|[String]||
|223|[Expression Tree Build.java](https://github.com/awangdev/LintCode/blob/master/Java/Expression%20Tree%20Build.java)|Hard|Java|[Binary Tree, Expression Tree, Minimum Binary Tree, Stack]||
|224|[Expression Evaluation.java](https://github.com/awangdev/LintCode/blob/master/Java/Expression%20Evaluation.java)|Hard|Java|[Binary Tree, DFS, Expression Tree, Minimum Binary Tree, Stack]||
|225|[Convert Expression to Polish Notation.java](https://github.com/awangdev/LintCode/blob/master/Java/Convert%20Expression%20to%20Polish%20Notation.java)|Hard|Java|[Binary Tree, DFS, Expression Tree, Stack]||
|226|[Convert Expression to Reverse Polish Notation.java](https://github.com/awangdev/LintCode/blob/master/Java/Convert%20Expression%20to%20Reverse%20Polish%20Notation.java)|Hard|Java|[Binary Tree, DFS, Expression Tree, Stack]||
|227|[Evaluate Reverse Polish Notation.java](https://github.com/awangdev/LintCode/blob/master/Java/Evaluate%20Reverse%20Polish%20Notation.java)|Medium|Java|[Stack]||
|228|[Decode Ways II.java](https://github.com/awangdev/LintCode/blob/master/Java/Decode%20Ways%20II.java)|Hard|Java|[DP, Enumeration, Partition DP]||
|229|[Palindrome Partitioning II.java](https://github.com/awangdev/LintCode/blob/master/Java/Palindrome%20Partitioning%20II.java)|Hard|Java|[DP, Partition DP]||
|230|[Backpack III.java](https://github.com/awangdev/LintCode/blob/master/Java/Backpack%20III.java)|Hard|Java|[Backpack DP, DP]||
|231|[First Missing Positive.java](https://github.com/awangdev/LintCode/blob/master/Java/First%20Missing%20Positive.java)|Hard|Java|[Array]||
|232|[Implement strStr().java](https://github.com/awangdev/LintCode/blob/master/Java/Implement%20strStr().java)|Easy|Java|[String, Two Pointers]||
|233|[Insertion Sort List.java](https://github.com/awangdev/LintCode/blob/master/Java/Insertion%20Sort%20List.java)|Medium|Java|[Linked List, Sort]||
|234|[Interleaving Positive and Negative Numbers.java](https://github.com/awangdev/LintCode/blob/master/Java/Interleaving%20Positive%20and%20Negative%20Numbers.java)|Medium|Java|[Two Pointers]||
|235|[Largest Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Largest%20Number.java)|Medium|Java|[Sort]||
|236|[Last Position of Target.java](https://github.com/awangdev/LintCode/blob/master/Java/Last%20Position%20of%20Target.java)|Easy|Java|[Binary Search]||
|237|[Length of Last Word.java](https://github.com/awangdev/LintCode/blob/master/Java/Length%20of%20Last%20Word.java)|Easy|Java|[String]||
|238|[Longest Common Substring.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Common%20Substring.java)|Medium|Java|[DP, Double Sequence DP, Sequence DP, String]||
|239|[Longest Increasing Continuous subsequence.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Increasing%20Continuous%20subsequence.java)|Easy|Java|[Array, Coordinate DP, DP]||
|240|[Longest Increasing Continuous subsequence II.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Increasing%20Continuous%20subsequence%20II.java)|Medium|Java|[Array, Coordinate DP, DP, Memoization]||
|241|[N-Queens.java](https://github.com/awangdev/LintCode/blob/master/Java/N-Queens.java)|Hard|Java|[Backtracking]||
|242|[N-Queens II.java](https://github.com/awangdev/LintCode/blob/master/Java/N-Queens%20II.java)|Hard|Java|[Backtracking]||
|243|[Maximum Subarray.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximum%20Subarray.java)|Easy|Java|[Array, DFS, DP, Divide and Conquer, PreSum, Sequence DP, Subarray]||
|244|[Maximum Subarray II.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximum%20Subarray%20II.java)|Medium|Java|[Array, DP, Greedy, PreSum, Sequence DP, Subarray]||
|245|[Median.java](https://github.com/awangdev/LintCode/blob/master/Java/Median.java)|Easy|Java|[Array, Quick Select, Quick Sort]||
|246|[Middle of Linked List.java](https://github.com/awangdev/LintCode/blob/master/Java/Middle%20of%20Linked%20List.java)|Easy|Java|[Linked List]||
|247|[Singleton.java](https://github.com/awangdev/LintCode/blob/master/Java/Singleton.java)|Easy|Java|[Design]||
|248|[Remove Linked List Elements.java](https://github.com/awangdev/LintCode/blob/master/Java/Remove%20Linked%20List%20Elements.java)|Easy|Java|[Linked List]||
|249|[Fibonacci.java](https://github.com/awangdev/LintCode/blob/master/Java/Fibonacci.java)|Easy|Java|[DP, Math, Memoization]||
|250|[Palindrome Linked List.java](https://github.com/awangdev/LintCode/blob/master/Java/Palindrome%20Linked%20List.java)|Easy|Java|[Linked List, Two Pointers]||
|251|[Reverse Linked List.java](https://github.com/awangdev/LintCode/blob/master/Java/Reverse%20Linked%20List.java)|Easy|Java|[Linked List]||
|252|[Reverse Linked List II .java](https://github.com/awangdev/LintCode/blob/master/Java/Reverse%20Linked%20List%20II%20.java)|Medium|Java|[Linked List]||
|253|[Intersection of Two Linked Lists.java](https://github.com/awangdev/LintCode/blob/master/Java/Intersection%20of%20Two%20Linked%20Lists.java)|Easy|Java|[Linked List]||
|254|[Palindrome Permutation.java](https://github.com/awangdev/LintCode/blob/master/Java/Palindrome%20Permutation.java)|Easy|Java|[Hash Table]||
|255|[Valid Palindrome.java](https://github.com/awangdev/LintCode/blob/master/Java/Valid%20Palindrome.java)|Easy|Java|[String, Two Pointers]||
|256|[Implement Stack using Queues.java](https://github.com/awangdev/LintCode/blob/master/Java/Implement%20Stack%20using%20Queues.java)|Easy|Java|[Design, Stack]||
|257|[Implement Stack.java](https://github.com/awangdev/LintCode/blob/master/Java/Implement%20Stack.java)|Easy|Java|[Stack]||
|258|[Invert Binary Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Invert%20Binary%20Tree.java)|Easy|Java|[BFS, DFS, Tree]||
|259|[Maximum Depth of Binary Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximum%20Depth%20of%20Binary%20Tree.java)|Easy|Java|[DFS, Tree]||
|260|[Minimum Depth of Binary Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Minimum%20Depth%20of%20Binary%20Tree.java)|Easy|Java|[BFS, DFS, Tree]||
|261|[Symmetric Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Symmetric%20Tree.java)|Easy|Java|[BFS, DFS, Tree]||
|262|[Tweaked Identical Binary Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Tweaked%20Identical%20Binary%20Tree.java)|Easy|Java|[DFS, Tree]||
|263|[Merge Two Binary Trees.java](https://github.com/awangdev/LintCode/blob/master/Java/Merge%20Two%20Binary%20Trees.java)|Easy|Java|[DFS, Tree]||
|264|[Subtree.java](https://github.com/awangdev/LintCode/blob/master/Java/Subtree.java)|Easy|Java|[DFS, Tree]||
|265|[Lowest Common Ancestor of a Binary Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Lowest%20Common%20Ancestor%20of%20a%20Binary%20Tree.java)|Medium|Java|[DFS, Tree]||
|266|[Lowest Common Ancestor II.java](https://github.com/awangdev/LintCode/blob/master/Java/Lowest%20Common%20Ancestor%20II.java)|Easy|Java|[Hash Table, Tree]||
|267|[Lowest Common Ancestor of a Binary Search Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Lowest%20Common%20Ancestor%20of%20a%20Binary%20Search%20Tree.java)|Medium|Java|[BST, DFS, Tree]||
|268|[Hash Function.java](https://github.com/awangdev/LintCode/blob/master/Java/Hash%20Function.java)|Easy|Java|[Hash Table]||
|269|[Merge Two Sorted Lists.java](https://github.com/awangdev/LintCode/blob/master/Java/Merge%20Two%20Sorted%20Lists.java)|Easy|Java|[Linked List]||
|270|[Missing Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Missing%20Number.java)|Easy|Java|[Array, Bit Manipulation, Math]||
|271|[LRU Cache.java](https://github.com/awangdev/LintCode/blob/master/Java/LRU%20Cache.java)|Hard|Java|[Design, Hash Table, Linked List]||
|272|[Remove Duplicates from Sorted Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Remove%20Duplicates%20from%20Sorted%20Array.java)|Easy|Java|[Array, Two Pointers]||
|273|[Remove Duplicates from Sorted Array II.java](https://github.com/awangdev/LintCode/blob/master/Java/Remove%20Duplicates%20from%20Sorted%20Array%20II.java)|Medium|Java|[Array, Two Pointers]||
|274|[Remove Duplicates from Sorted List.java](https://github.com/awangdev/LintCode/blob/master/Java/Remove%20Duplicates%20from%20Sorted%20List.java)|Easy|Java|[Linked List]||
|275|[Remove Duplicates from Sorted List II.java](https://github.com/awangdev/LintCode/blob/master/Java/Remove%20Duplicates%20from%20Sorted%20List%20II.java)|Medium|Java|[Linked List]||
|276|[QuickSort.java](https://github.com/awangdev/LintCode/blob/master/Java/QuickSort.java)|Medium|Java|[Quick Sort, Sort]||
|277|[MergeSort.java](https://github.com/awangdev/LintCode/blob/master/Java/MergeSort.java)|Medium|Java|[Merge Sort, Sort]||
|278|[Longest Word in Dictionary.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Word%20in%20Dictionary.java)|Easy|Java|[Hash Table, Trie]||
|279|[Binary Tree Level Order Traversal.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Level%20Order%20Traversal.java)|Medium|Java|[BFS, DFS, Tree]||
|280|[Binary Tree Level Order Traversal II.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Level%20Order%20Traversal%20II.java)|Medium|Java|[BFS, Tree]||
|281|[Binary Tree Longest Consecutive Sequence II.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Longest%20Consecutive%20Sequence%20II.java)|Medium|Java|[DFS, Divide and Conquer, Double Recursive, Tree]||
|282|[Binary Tree Maximum Path Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Maximum%20Path%20Sum.java)|Hard|Java|[DFS, DP, Tree, Tree DP]||
|283|[Path Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Path%20Sum.java)|Easy|Java|[DFS, Tree]||
|284|[Path Sum II.java](https://github.com/awangdev/LintCode/blob/master/Java/Path%20Sum%20II.java)|Easy|Java|[Backtracking, DFS, Tree]||
|285|[Path Sum III.java](https://github.com/awangdev/LintCode/blob/master/Java/Path%20Sum%20III.java)|Easy|Java|[DFS, Double Recursive, Tree]||
|286|[Rotate String.java](https://github.com/awangdev/LintCode/blob/master/Java/Rotate%20String.java)|Easy|Java|[String]||
|287|[Combinations.java](https://github.com/awangdev/LintCode/blob/master/Java/Combinations.java)|Medium|Java|[Backtracking, Combination, DFS]||
|288|[Combination Sum IV.java](https://github.com/awangdev/LintCode/blob/master/Java/Combination%20Sum%20IV.java)|Medium|Java|[Array, Backpack DP, DP]||
|289|[Binary Tree Right Side View.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Right%20Side%20View.java)|Medium|Java|[BFS, DFS, Tree]||
|290|[Binary Tree Maximum Path Sum II.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Maximum%20Path%20Sum%20II.java)|Medium|Java|[DFS, Tree]||
|291|[Rotate List.java](https://github.com/awangdev/LintCode/blob/master/Java/Rotate%20List.java)|Medium|Java|[Linked List, Two Pointers]||
|292|[Basic Calculator.java](https://github.com/awangdev/LintCode/blob/master/Java/Basic%20Calculator.java)|Hard|Java|[Binary Tree, Expression Tree, Math, Minimum Binary Tree, Stack]||
|293|[Longest Consecutive Sequence.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Consecutive%20Sequence.java)|Hard|Java|[Array, Hash Table, Union Find]||
|294|[Binary Tree Longest Consecutive Sequence.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Longest%20Consecutive%20Sequence.java)|Medium|Java|[DFS, Divide and Conquer, Tree]||
|295|[Number of Connected Components in an Undirected Graph.java](https://github.com/awangdev/LintCode/blob/master/Java/Number%20of%20Connected%20Components%20in%20an%20Undirected%20Graph.java)|Medium|Java|[BFS, DFS, Graph, Union Find]||
|296|[Next Closest Time.java](https://github.com/awangdev/LintCode/blob/master/Java/Next%20Closest%20Time.java)|Medium|Java|[Basic Implementation, Enumeration, String]||
|297|[Serialize and Deserialize Binary Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Serialize%20and%20Deserialize%20Binary%20Tree.java)|Hard|Java|[BFS, DFS, Deque, Design, Divide and Conquer, Tree]||
|298|[Partition Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Partition%20Array.java)|Medium|Java|[Array, Quick Sort, Sort, Two Pointers]||
|299|[Word Ladder.java](https://github.com/awangdev/LintCode/blob/master/Java/Word%20Ladder.java)|Medium|Java|[BFS]||
|300|[Unique Word Abbreviation.java](https://github.com/awangdev/LintCode/blob/master/Java/Unique%20Word%20Abbreviation.java)|Medium|Java|[Design, Hash Table]||
|301|[Unique Binary Search Tree II.java](https://github.com/awangdev/LintCode/blob/master/Java/Unique%20Binary%20Search%20Tree%20II.java)|Medium|Java|[BST, DP, Divide and Conquer, Tree]||
|302|[Ugly Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Ugly%20Number.java)|Medium|Java|[Math]||
|303|[Top K Frequent Words.java](https://github.com/awangdev/LintCode/blob/master/Java/Top%20K%20Frequent%20Words.java)|Medium|Java|[Hash Table, Heap, MaxHeap, MinHeap, PriorityQueue, Trie]||
|304|[Segment Tree Build.java](https://github.com/awangdev/LintCode/blob/master/Java/Segment%20Tree%20Build.java)|Medium|Java|[Binary Tree, Divide and Conquer, Lint, Segment Tree]||
|305|[Segment Tree Build II.java](https://github.com/awangdev/LintCode/blob/master/Java/Segment%20Tree%20Build%20II.java)|Medium|Java|[Binary Tree, Divide and Conquer, Lint, Segment Tree]||
|306|[Segment Tree Query.java](https://github.com/awangdev/LintCode/blob/master/Java/Segment%20Tree%20Query.java)|Medium|Java|[Binary Tree, DFS, Divide and Conquer, Lint, Segment Tree]||
|307|[Segment Tree Modify.java](https://github.com/awangdev/LintCode/blob/master/Java/Segment%20Tree%20Modify.java)|Medium|Java|[Binary Tree, DFS, Divide and Conquer, Lint, Segment Tree]||
|308|[Segment Tree Query II.java](https://github.com/awangdev/LintCode/blob/master/Java/Segment%20Tree%20Query%20II.java)|Medium|Java|[Binary Tree, DFS, Divide and Conquer, Lint, Segment Tree]||
|309|[Count of Smaller Numbers After Self.java](https://github.com/awangdev/LintCode/blob/master/Java/Count%20of%20Smaller%20Numbers%20After%20Self.java)|Hard|Java|[BST, Binary Indexed Tree, Binary Search, Divide and Conquer, Segment Tree]||
|310|[ColorGrid.java](https://github.com/awangdev/LintCode/blob/master/Java/ColorGrid.java)|Medium|Java|[Design, Hash Table]||
|311|[Container With Most Water.java](https://github.com/awangdev/LintCode/blob/master/Java/Container%20With%20Most%20Water.java)|Medium|Java|[Array, Two Pointers]||
|312|[Copy List with Random Pointer.java](https://github.com/awangdev/LintCode/blob/master/Java/Copy%20List%20with%20Random%20Pointer.java)|Medium|Java|[Hash Table, Linked List]||
|313|[Encode and Decode Strings.java](https://github.com/awangdev/LintCode/blob/master/Java/Encode%20and%20Decode%20Strings.java)|Medium|Java|[String]||
|314|[Fast Power.java](https://github.com/awangdev/LintCode/blob/master/Java/Fast%20Power.java)|Medium|Java|[DFS, Divide and Conquer]||
|315|[Find the Connected Component in the Undirected Graph.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20the%20Connected%20Component%20in%20the%20Undirected%20Graph.java)|Medium|Java|[BFS, DFS]||
|316|[HashWithCustomizedClass(LinkedList).java](https://github.com/awangdev/LintCode/blob/master/Java/HashWithCustomizedClass(LinkedList).java)|Medium|Java|[Hash Table]||
|317|[Interval Minimum Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Interval%20Minimum%20Number.java)|Medium|Java|[Binary Search, Divide and Conquer, Lint, Segment Tree]||
|318|[Interval Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Interval%20Sum.java)|Medium|Java|[Binary Search, Lint, Segment Tree]||
|319|[Kth Smallest Element in a BST.java](https://github.com/awangdev/LintCode/blob/master/Java/Kth%20Smallest%20Element%20in%20a%20BST.java)|Medium|Java|[BST, DFS, Stack, Tree]||
|320|[Longest Common Prefix.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Common%20Prefix.java)|Easy|Java|[String]||
|321|[Majority Element II.java](https://github.com/awangdev/LintCode/blob/master/Java/Majority%20Element%20II.java)|Medium|Java|[Array]||
|322|[Partition List.java](https://github.com/awangdev/LintCode/blob/master/Java/Partition%20List.java)|Medium|Java|[Linked List, Two Pointers]||
|323|[Peeking Iterator.java](https://github.com/awangdev/LintCode/blob/master/Java/Peeking%20Iterator.java)|Medium|Java|[Design]||
|324|[Rehashing.java](https://github.com/awangdev/LintCode/blob/master/Java/Rehashing.java)|Medium|Java|[Hash Table]||
|325|[Reorder List.java](https://github.com/awangdev/LintCode/blob/master/Java/Reorder%20List.java)|Medium|Java|[Linked List]||
|326|[Restore IP Addresses.java](https://github.com/awangdev/LintCode/blob/master/Java/Restore%20IP%20Addresses.java)|Medium|Java|[Backtracking, DFS, String]||
|327|[Reverse Words in a String.java](https://github.com/awangdev/LintCode/blob/master/Java/Reverse%20Words%20in%20a%20String.java)|Medium|Java|[String]||
|328|[Reverse Words in a String II.java](https://github.com/awangdev/LintCode/blob/master/Java/Reverse%20Words%20in%20a%20String%20II.java)|Medium|Java|[String]||
|329|[Reverse Words in a String III.java](https://github.com/awangdev/LintCode/blob/master/Java/Reverse%20Words%20in%20a%20String%20III.java)|Easy|Java|[String]||
|330|[Search a 2D Matrix.java](https://github.com/awangdev/LintCode/blob/master/Java/Search%20a%202D%20Matrix.java)|Medium|Java|[Array, Binary Search]||
|331|[Search a 2D Matrix II.java](https://github.com/awangdev/LintCode/blob/master/Java/Search%20a%202D%20Matrix%20II.java)|Medium|Java|[Binary Search, Divide and Conquer]||
|332|[Search for a Range.java](https://github.com/awangdev/LintCode/blob/master/Java/Search%20for%20a%20Range.java)|Medium|Java|[Array, Binary Search]||
|333|[Search Range in Binary Search Tree .java](https://github.com/awangdev/LintCode/blob/master/Java/Search%20Range%20in%20Binary%20Search%20Tree%20.java)|Medium|Java|[BST, Binary Tree]||
|334|[Merge Sorted Array II.java](https://github.com/awangdev/LintCode/blob/master/Java/Merge%20Sorted%20Array%20II.java)|Easy|Java|[Array]||
|335|[Nth to Last Node in List.java](https://github.com/awangdev/LintCode/blob/master/Java/Nth%20to%20Last%20Node%20in%20List.java)|Easy|Java|[Linked List]||
|336|[Sort List.java](https://github.com/awangdev/LintCode/blob/master/Java/Sort%20List.java)|Medium|Java|[Divide and Conquer, Linked List, Merge Sort, Sort]||
|337|[Summary Ranges.java](https://github.com/awangdev/LintCode/blob/master/Java/Summary%20Ranges.java)|Medium|Java|[Array]||
|338|[Topological Sorting.java](https://github.com/awangdev/LintCode/blob/master/Java/Topological%20Sorting.java)|Medium|Java|[BFS, DFS, Topological Sort]||
|339|[Remove Duplicate Letters.java](https://github.com/awangdev/LintCode/blob/master/Java/Remove%20Duplicate%20Letters.java)|Hard|Java|[Greedy, Hash Table, Stack]||
|340|[Spiral Matrix.java](https://github.com/awangdev/LintCode/blob/master/Java/Spiral%20Matrix.java)|Medium|Java|[Array, Enumeration]||
|341|[Expression Add Operators.java](https://github.com/awangdev/LintCode/blob/master/Java/Expression%20Add%20Operators.java)|Hard|Java|[Backtracking, DFS, Divide and Conquer, String]||
|342|[Insert Interval.java](https://github.com/awangdev/LintCode/blob/master/Java/Insert%20Interval.java)|Hard|Java|[Array, PriorityQueue, Sort]||
|343|[Shortest Palindrome.java](https://github.com/awangdev/LintCode/blob/master/Java/Shortest%20Palindrome.java)|Hard|Java|[KMP, String]||
|344|[Two Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Two%20Sum.java)|Easy|Java|[Array, Hash Table]||
|345|[K Empty Slots.java](https://github.com/awangdev/LintCode/blob/master/Java/K%20Empty%20Slots.java)|Hard|Java|[Array, BST, TreeSet]||
|346|[Count of Range Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Count%20of%20Range%20Sum.java)|Hard|Java|[BST, Divide and Conquer, Merge Sort, PreSum]||
|347|[Max Sum of Rectangle No Larger Than K.java](https://github.com/awangdev/LintCode/blob/master/Java/Max%20Sum%20of%20Rectangle%20No%20Larger%20Than%20K.java)|Hard|Java|[Array, BST, Binary Search, DP, Queue, TreeSet]||
|348|[Perfect Rectangle.java](https://github.com/awangdev/LintCode/blob/master/Java/Perfect%20Rectangle.java)|Hard|Java|[Design, Geometry, Hash Table]||
|349|[Construct Binary Tree from Inorder and Postorder Traversal.java](https://github.com/awangdev/LintCode/blob/master/Java/Construct%20Binary%20Tree%20from%20Inorder%20and%20Postorder%20Traversal.java)|Medium|Java|[Array, DFS, Divide and Conquer, Tree]||
|350|[Generate Parentheses.java](https://github.com/awangdev/LintCode/blob/master/Java/Generate%20Parentheses.java)|Medium|Java|[Backtracking, DFS, Sequence DFS, String]||
|351|[Strobogrammatic Number II.java](https://github.com/awangdev/LintCode/blob/master/Java/Strobogrammatic%20Number%20II.java)|Medium|Java|[DFS, Enumeration, Math, Sequence DFS]||
|352|[Flip Game II.java](https://github.com/awangdev/LintCode/blob/master/Java/Flip%20Game%20II.java)|Medium|Java|[Backtracking, DFS, DP]||
|353|[Max Area of Island.java](https://github.com/awangdev/LintCode/blob/master/Java/Max%20Area%20of%20Island.java)|Easy|Java|[Array, DFS]||
|354|[Max Points on a Line.java](https://github.com/awangdev/LintCode/blob/master/Java/Max%20Points%20on%20a%20Line.java)|Hard|Java|[Array, Geometry, Hash Table, Math]||
|355|[Number of Digit One.java](https://github.com/awangdev/LintCode/blob/master/Java/Number%20of%20Digit%20One.java)|Hard|Java|[Math]||
|356|[Binary Representation.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Representation.java)|Hard|Java|[Bit Manipulation, String]||
|357|[Palindrome Partitioning.java](https://github.com/awangdev/LintCode/blob/master/Java/Palindrome%20Partitioning.java)|Medium|Java|[Backtracking, DFS]||
|358|[Recover Binary Search Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Recover%20Binary%20Search%20Tree.java)|Hard|Java|[BST, DFS, Tree]||
|359|[Subarray Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Subarray%20Sum.java)|Easy|Java|[Array, Hash Table, PreSum, Subarray]||
|360|[Submatrix Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Submatrix%20Sum.java)|Medium|Java|[Array, Hash Table, PreSum]||
|361|[Longest Palindromic Substring.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Palindromic%20Substring.java)|Medium|Java|[DP, String]||
|362|[Longest Palindromic Subsequence.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Palindromic%20Subsequence.java)|Medium|Java|[DFS, DP, Interval DP, Memoization]||
|363|[Jump Game II.java](https://github.com/awangdev/LintCode/blob/master/Java/Jump%20Game%20II.java)|Hard|Java|[Array, Coordinate DP, DP, Greedy]||
|364|[Gas Station.java](https://github.com/awangdev/LintCode/blob/master/Java/Gas%20Station.java)|Medium|Java|[Greedy]||
|365|[Triangles.java](https://github.com/awangdev/LintCode/blob/master/Java/Triangles.java)|Medium|Java|[Array, Coordinate DP, DFS, DP, Memoization]||
|366|[Range Sum Query - Immutable.java](https://github.com/awangdev/LintCode/blob/master/Java/Range%20Sum%20Query%20-%20Immutable.java)|Easy|Java|[DP, PreSum]||
|367|[Longest Valid Parentheses.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Valid%20Parentheses.java)|Hard|Java|[Coordinate DP, Stack, String]||
|368|[Remove Invalid Parentheses.java](https://github.com/awangdev/LintCode/blob/master/Java/Remove%20Invalid%20Parentheses.java)|Review|Java|[BFS, DFS, DP]||
|369|[Merge Intervals.java](https://github.com/awangdev/LintCode/blob/master/Java/Merge%20Intervals.java)|Medium|Java|[Array, PriorityQueue, Sort, Sweep Line]||
|370|[H-Index.java](https://github.com/awangdev/LintCode/blob/master/Java/H-Index.java)|Medium|Java|[Bucket Sort, Hash Table, Sort]||
|371|[H-Index II.java](https://github.com/awangdev/LintCode/blob/master/Java/H-Index%20II.java)|Medium|Java|[Binary Search]||
|372|[Sort Colors.java](https://github.com/awangdev/LintCode/blob/master/Java/Sort%20Colors.java)|Medium|Java|[Array, Partition, Quick Sort, Sort, Two Pointers]||
|373|[Sort Colors II.java](https://github.com/awangdev/LintCode/blob/master/Java/Sort%20Colors%20II.java)|Medium|Java|[Partition, Quick Sort, Sort, Two Pointers]||
|374|[Sort Letters by Case.java](https://github.com/awangdev/LintCode/blob/master/Java/Sort%20Letters%20by%20Case.java)|Medium|Java|[Partition, Sort, String, Two Pointers]||
|375|[Subarray Sum Closest.java](https://github.com/awangdev/LintCode/blob/master/Java/Subarray%20Sum%20Closest.java)|Medium|Java|[PreSum, PriorityQueue, Sort, Subarray]||
|376|[Task Scheduler.java](https://github.com/awangdev/LintCode/blob/master/Java/Task%20Scheduler.java)|Medium|Java|[Array, Enumeration, Greedy, PriorityQueue, Queue]||
|377|[Rearrange String k Distance Apart.java](https://github.com/awangdev/LintCode/blob/master/Java/Rearrange%20String%20k%20Distance%20Apart.java)|Hard|Java|[Greedy, Hash Table, Heap]||
|378|[Exam Room.java](https://github.com/awangdev/LintCode/blob/master/Java/Exam%20Room.java)|Medium|Java|[PriorityQueue, Sort]||
|379|[Anagrams.java](https://github.com/awangdev/LintCode/blob/master/Java/Anagrams.java)|Medium|Java|[Array, Hash Table]||
|380|[Path Sum IV.java](https://github.com/awangdev/LintCode/blob/master/Java/Path%20Sum%20IV.java)|Medium|Java|[DFS, Hash Table, Tree]||
|381|[Longest Words.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Words.java)|Easy|Java|[Hash Table, String]||
|382|[Unique Characters.java](https://github.com/awangdev/LintCode/blob/master/Java/Unique%20Characters.java)|Easy|Java|[Array, String]||
|383|[Number Of Corner Rectangles.java](https://github.com/awangdev/LintCode/blob/master/Java/Number%20Of%20Corner%20Rectangles.java)|Medium|Java|[DP, Math]||
|384|[Palindromic Substrings.java](https://github.com/awangdev/LintCode/blob/master/Java/Palindromic%20Substrings.java)|Medium|Java|[DP, String]||
|385|[Multiply Strings.java](https://github.com/awangdev/LintCode/blob/master/Java/Multiply%20Strings.java)|Medium|Java|[Math, String]||
|386|[Subsets.java](https://github.com/awangdev/LintCode/blob/master/Java/Subsets.java)|Medium|Java|[Array, BFS, Backtracking, Bit Manipulation, DFS]||
|387|[Subsets II.java](https://github.com/awangdev/LintCode/blob/master/Java/Subsets%20II.java)|Medium|Java|[Array, BFS, Backtracking, DFS]||
|388|[Combination Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Combination%20Sum.java)|Medium|Java|[Array, Backtracking, Combination, DFS]||
|389|[Combination Sum II.java](https://github.com/awangdev/LintCode/blob/master/Java/Combination%20Sum%20II.java)|Medium|Java|[Array, Backtracking, Combination, DFS]||
|390|[Combination Sum III.java](https://github.com/awangdev/LintCode/blob/master/Java/Combination%20Sum%20III.java)|Medium|Java|[Array, Backtracking, Combination, DFS]||
|391|[Product of Array Except Self.java](https://github.com/awangdev/LintCode/blob/master/Java/Product%20of%20Array%20Except%20Self.java)|Medium|Java|[Array, PreProduct]||
|392|[Total Hamming Distance.java](https://github.com/awangdev/LintCode/blob/master/Java/Total%20Hamming%20Distance.java)|Medium|Java|[Bit Manipulation]||
|393|[Smallest Subtree with all the Deepest Nodes.java](https://github.com/awangdev/LintCode/blob/master/Java/Smallest%20Subtree%20with%20all%20the%20Deepest%20Nodes.java)|Medium|Java|[DFS, Divide and Conquer, Tree]||
|394|[Binary Gap.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Gap.java)|Easy|Java|[Bit Manipulation]||
|395|[Subarray Sum Equals K.java](https://github.com/awangdev/LintCode/blob/master/Java/Subarray%20Sum%20Equals%20K.java)|Medium|Java|[Array, Hash Table, PreSum, Subarray]||
|396|[Maximize Distance to Closest Person.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximize%20Distance%20to%20Closest%20Person.java)|Easy|Java|[Array]||
|397|[Simplify Path.java](https://github.com/awangdev/LintCode/blob/master/Java/Simplify%20Path.java)|Medium|Java|[Stack, String]||
|398|[Convert Binary Search Tree to Sorted Doubly Linked List (extra space).java](https://github.com/awangdev/LintCode/blob/master/Java/Convert%20Binary%20Search%20Tree%20to%20Sorted%20Doubly%20Linked%20List%20(extra%20space).java)|Medium|Java|[Linked List, Stack, Tree]||
|399|[Paint Fence.java](https://github.com/awangdev/LintCode/blob/master/Java/Paint%20Fence.java)|Easy|Java|[DP, Sequence DP]||
|400|[Binary Tree Zigzag Level Order Traversal.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Zigzag%20Level%20Order%20Traversal.java)|Medium|Java|[BFS, Stack, Tree]||
|401|[Word Break.java](https://github.com/awangdev/LintCode/blob/master/Java/Word%20Break.java)|Medium|Java|[DP, Hash Table, Sequence DP]||
|402|[Best Time to Buy and Sell Stock.java](https://github.com/awangdev/LintCode/blob/master/Java/Best%20Time%20to%20Buy%20and%20Sell%20Stock.java)|Easy|Java|[Array, DP, Sequence DP]||
|403|[Best Time to Buy and Sell Stock II.java](https://github.com/awangdev/LintCode/blob/master/Java/Best%20Time%20to%20Buy%20and%20Sell%20Stock%20II.java)|Easy|Java|[Array, DP, Greedy, Sequence DP, Status DP]||
|404|[Longest Increasing Subsequence.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Increasing%20Subsequence.java)|Medium|Java|[Binary Search, Coordinate DP, DP, Memoization]||
|405|[Best Time to Buy and Sell Stock with Transaction Fee.java](https://github.com/awangdev/LintCode/blob/master/Java/Best%20Time%20to%20Buy%20and%20Sell%20Stock%20with%20Transaction%20Fee.java)|Medium|Java|[Array, DP, Greedy, Sequence DP, Status DP]||
|406|[Random Pick Index.java](https://github.com/awangdev/LintCode/blob/master/Java/Random%20Pick%20Index.java)|Medium|Java|[Reservior Sampling]||
|407|[Find the Celebrity.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20the%20Celebrity.java)|Medium|Java|[Array, Greedy]||
|408|[Sparse Matrix Multiplication.java](https://github.com/awangdev/LintCode/blob/master/Java/Sparse%20Matrix%20Multiplication.java)|Medium|Java|[Hash Table]||
|409|[Brick Wall.java](https://github.com/awangdev/LintCode/blob/master/Java/Brick%20Wall.java)|Medium|Java|[Hash Table]||
|410|[Exclusive Time of Functions.java](https://github.com/awangdev/LintCode/blob/master/Java/Exclusive%20Time%20of%20Functions.java)|Medium|Java|[Stack]||
|411|[Friends Of Appropriate Ages.java](https://github.com/awangdev/LintCode/blob/master/Java/Friends%20Of%20Appropriate%20Ages.java)|Medium|Java|[Array, Math]||
|412|[Target Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/Target%20Sum.java)|Medium|Java|[DFS, DP]||
|413|[Maximum Size Subarray Sum Equals k.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximum%20Size%20Subarray%20Sum%20Equals%20k.java)|Medium|Java|[Hash Table, PreSum, Subarray]||
|414|[Contiguous Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Contiguous%20Array.java)|Medium|Java|[Hash Table]||
|415|[Line Reflection.java](https://github.com/awangdev/LintCode/blob/master/Java/Line%20Reflection.java)|Medium|Java|[Hash Table, Math]||
|416|[Insert Delete GetRandom O(1).java](https://github.com/awangdev/LintCode/blob/master/Java/Insert%20Delete%20GetRandom%20O(1).java)|Medium|Java|[Array, Design, Hash Table]||
|417|[Number of Longest Increasing Subsequence.java](https://github.com/awangdev/LintCode/blob/master/Java/Number%20of%20Longest%20Increasing%20Subsequence.java)|Medium|Java|[Coordinate DP, DP]||
|418|[Minimum Swaps To Make Sequences Increasing.java](https://github.com/awangdev/LintCode/blob/master/Java/Minimum%20Swaps%20To%20Make%20Sequences%20Increasing.java)|Medium|Java|[Coordinate DP, DP, Status DP]||
|419|[Binary Tree Vertical Order Traversal.java](https://github.com/awangdev/LintCode/blob/master/Java/Binary%20Tree%20Vertical%20Order%20Traversal.java)|Medium|Java|[BFS, DFS, Hash Table, Tree]||
|420|[Populating Next Right Pointers in Each Node II.java](https://github.com/awangdev/LintCode/blob/master/Java/Populating%20Next%20Right%20Pointers%20in%20Each%20Node%20II.java)|Medium|Java|[DFS, Tree]||
|421|[Search in Rotated Sorted Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Search%20in%20Rotated%20Sorted%20Array.java)|Medium|Java|[Array, Binary Search]||
|422|[Minimum Subarray.java](https://github.com/awangdev/LintCode/blob/master/Java/Minimum%20Subarray.java)|Easy|Java|[Array, DP, Greedy, Sequence DP, Subarray]||
|423|[Valid Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Valid%20Number.java)|Hard|Java|[Enumeration, Math, String]||
|424|[Find the Weak Connected Component in the Directed Graph.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20the%20Weak%20Connected%20Component%20in%20the%20Directed%20Graph.java)|Medium|Java|[Union Find]||
|425|[Accounts Merge.java](https://github.com/awangdev/LintCode/blob/master/Java/Accounts%20Merge.java)|Medium|Java|[DFS, Hash Table, Hash Table, Union Find]||
|426|[Bricks Falling When Hit.java](https://github.com/awangdev/LintCode/blob/master/Java/Bricks%20Falling%20When%20Hit.java)|Hard|Java|[Union Find]||
|427|[Interval Sum II.java](https://github.com/awangdev/LintCode/blob/master/Java/Interval%20Sum%20II.java)|Hard|Java|[Binary Search, Lint, Segment Tree]||
|428|[Count of Smaller Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Count%20of%20Smaller%20Number.java)|Medium|Java|[Binary Search, Lint, Segment Tree]||
|429|[HashHeap.java](https://github.com/awangdev/LintCode/blob/master/Java/HashHeap.java)|Hard|Java|[HashHeap, Heap]||
|430|[My Calendar I.java](https://github.com/awangdev/LintCode/blob/master/Java/My%20Calendar%20I.java)|Medium|Java|[Array, TreeMap]||
|431|[Reverse Pairs.java](https://github.com/awangdev/LintCode/blob/master/Java/Reverse%20Pairs.java)|Medium|Java|[Binary Indexed Tree, Binary Search Tree, Divide and Conquer, Merge Sort, Segment Tree]||
|432|[Trapping Rain Water II.java](https://github.com/awangdev/LintCode/blob/master/Java/Trapping%20Rain%20Water%20II.java)|Hard|Java|[BFS, Heap, MinHeap, PriorityQueue]||
|433|[Kth Largest Element in an Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Kth%20Largest%20Element%20in%20an%20Array.java)|Medium|Java|[Divide and Conquer, Heap, MinHeap, PriorityQueue, Quick Sort]||
|434|[Merge k Sorted Lists.java](https://github.com/awangdev/LintCode/blob/master/Java/Merge%20k%20Sorted%20Lists.java)|Medium|Java|[Divide and Conquer, Heap, Linked List, PriorityQueue]||
|435|[Merge k Sorted Arrays.java](https://github.com/awangdev/LintCode/blob/master/Java/Merge%20k%20Sorted%20Arrays.java)|Medium|Java|[Heap, MinHeap, PriorityQueue]||
|436|[Heapify.java](https://github.com/awangdev/LintCode/blob/master/Java/Heapify.java)|Medium|Java|[Heap, MinHeap]||
|437|[Top K Frequent Elements.java](https://github.com/awangdev/LintCode/blob/master/Java/Top%20K%20Frequent%20Elements.java)|Medium|Java|[Hash Table, Heap, MaxHeap, MinHeap, PriorityQueue]||
|438|[Ugly Number II.java](https://github.com/awangdev/LintCode/blob/master/Java/Ugly%20Number%20II.java)|Medium|Java|[DP, Enumeration, Heap, Math, PriorityQueue]||
|439|[Find Median from Data Stream.java](https://github.com/awangdev/LintCode/blob/master/Java/Find%20Median%20from%20Data%20Stream.java)|Hard|Java|[Design, Heap, MaxHeap, MinHeap]||
|440|[Sliding Window Median.java](https://github.com/awangdev/LintCode/blob/master/Java/Sliding%20Window%20Median.java)|Hard|Java|[Design, Heap, MaxHeap, MinHeap, Sliding Window]||
|441|[Inorder Successor in BST.java](https://github.com/awangdev/LintCode/blob/master/Java/Inorder%20Successor%20in%20BST.java)|Medium|Java|[BST, Tree]||
|442|[Subtree of Another Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Subtree%20of%20Another%20Tree.java)|Easy|Java|[DFS, Divide and Conquer, Tree]||
|443|[Two Sum IV - Input is a BST.java](https://github.com/awangdev/LintCode/blob/master/Java/Two%20Sum%20IV%20-%20Input%20is%20a%20BST.java)|Easy|Java|[Tree]||
|444|[Read N Characters Given Read4.java](https://github.com/awangdev/LintCode/blob/master/Java/Read%20N%20Characters%20Given%20Read4.java)|Easy|Java|[Enumeration, String]||
|445|[Design Search Autocomplete System.java](https://github.com/awangdev/LintCode/blob/master/Java/Design%20Search%20Autocomplete%20System.java)|Hard|Java|[Design, Hash Table, MinHeap, PriorityQueue, Trie]||
|446|[Walls and Gates.java](https://github.com/awangdev/LintCode/blob/master/Java/Walls%20and%20Gates.java)|Medium|Java|[BFS, DFS]||
|447|[Merge Sorted Array.java](https://github.com/awangdev/LintCode/blob/master/Java/Merge%20Sorted%20Array.java)|Easy|Java|[Array, Two Pointers]||
|448|[Integer to English Words.java](https://github.com/awangdev/LintCode/blob/master/Java/Integer%20to%20English%20Words.java)|Hard|Java|[Enumeration, Math, String]||
|449|[Alien Dictionary.java](https://github.com/awangdev/LintCode/blob/master/Java/Alien%20Dictionary.java)|Hard|Java|[BFS, Backtracking, DFS, Graph, Topological Sort]||
|450|[Valid Palindrome II.java](https://github.com/awangdev/LintCode/blob/master/Java/Valid%20Palindrome%20II.java)|Easy|Java|[String]||
|451|[Convert Binary Search Tree to Sorted Doubly Linked List.java](https://github.com/awangdev/LintCode/blob/master/Java/Convert%20Binary%20Search%20Tree%20to%20Sorted%20Doubly%20Linked%20List.java)|Medium|Java|[BST, DFS, Divide and Conquer, Linked List, Tree]||
|452|[Word Ladder II.java](https://github.com/awangdev/LintCode/blob/master/Java/Word%20Ladder%20II.java)|Hard|Java|[Array, BFS, Backtracking, DFS, Hash Table, String]||
|453|[Moving Average from Data Stream.java](https://github.com/awangdev/LintCode/blob/master/Java/Moving%20Average%20from%20Data%20Stream.java)|Easy|Java|[Design, Queue, Sliding Window]||
|454|[Move Zeroes.java](https://github.com/awangdev/LintCode/blob/master/Java/Move%20Zeroes.java)|Easy|Java|[Array, Two Pointers]||
|455|[Flood Fill.java](https://github.com/awangdev/LintCode/blob/master/Java/Flood%20Fill.java)|Easy|Java|[DFS]||
|456|[Diameter of Binary Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Diameter%20of%20Binary%20Tree.java)|Easy|Java|[Tree]||
|457|[Backspace String Compare.java](https://github.com/awangdev/LintCode/blob/master/Java/Backspace%20String%20Compare.java)|Easy|Java|[Stack, Two Pointers]||
|458|[Text Justification.java](https://github.com/awangdev/LintCode/blob/master/Java/Text%20Justification.java)|Hard|Java|[Enumeration, String]||
|459|[Read N Characters Given Read4 II - Call multiple times.java](https://github.com/awangdev/LintCode/blob/master/Java/Read%20N%20Characters%20Given%20Read4%20II%20-%20Call%20multiple%20times.java)|Hard|Java|[Enumeration, String]||
|460|[Frog Jump.java](https://github.com/awangdev/LintCode/blob/master/Java/Frog%20Jump.java)|Hard|Java|[DP, Hash Table]||
|461|[Longest Substring with At Most Two Distinct Characters.java](https://github.com/awangdev/LintCode/blob/master/Java/Longest%20Substring%20with%20At%20Most%20Two%20Distinct%20Characters.java)|Hard|Java|[Hash Table, Sliding Window, String, Two Pointers]||
|462|[Shortest Distance from All Buildings.java](https://github.com/awangdev/LintCode/blob/master/Java/Shortest%20Distance%20from%20All%20Buildings.java)|Hard|Java|[BFS]||
|463|[String to Integer (atoi).java](https://github.com/awangdev/LintCode/blob/master/Java/String%20to%20Integer%20(atoi).java)|Medium|Java|[Math, String]||
|464|[Roman to Integer.java](https://github.com/awangdev/LintCode/blob/master/Java/Roman%20to%20Integer.java)|Easy|Java|[Math, String]||
|465|[Intersection of Two Arrays.java](https://github.com/awangdev/LintCode/blob/master/Java/Intersection%20of%20Two%20Arrays.java)|Easy|Java|[Binary Search, Hash Table, Sort, Two Pointers]||
|466|[Strobogrammatic Number.java](https://github.com/awangdev/LintCode/blob/master/Java/Strobogrammatic%20Number.java)|Easy|Java|[Enumeration, Hash Table, Math]||
|467|[Valid Parentheses.java](https://github.com/awangdev/LintCode/blob/master/Java/Valid%20Parentheses.java)|Easy|Java|[Stack, String]||
|468|[First Unique Character in a String.java](https://github.com/awangdev/LintCode/blob/master/Java/First%20Unique%20Character%20in%20a%20String.java)|Easy|Java|[Hash Table, String]||
|469|[Add Binary.java](https://github.com/awangdev/LintCode/blob/master/Java/Add%20Binary.java)|Easy|Java|[Math, String, Two Pointers]||
|470|[Clone Graph.java](https://github.com/awangdev/LintCode/blob/master/Java/Clone%20Graph.java)|Medium|Java|[BFS, DFS, Graph]||
|471|[Sliding Window Maximum.java](https://github.com/awangdev/LintCode/blob/master/Java/Sliding%20Window%20Maximum.java)|Hard|Java|[Deque, Heap, Sliding Window]||
|472|[Median of Two Sorted Arrays.java](https://github.com/awangdev/LintCode/blob/master/Java/Median%20of%20Two%20Sorted%20Arrays.java)|Hard|Java|[Array, Binary Search, DFS, Divide and Conquer]||
|473|[Permutations.java](https://github.com/awangdev/LintCode/blob/master/Java/Permutations.java)|Medium|Java|[Backtracking, DFS, Permutation]||
|474|[One Edit Distance.java](https://github.com/awangdev/LintCode/blob/master/Java/One%20Edit%20Distance.java)|Medium|Java|[String]||
|475|[4Sum.java](https://github.com/awangdev/LintCode/blob/master/Java/4Sum.java)|Medium|Java|[Hash Table]||
|476|[Bus Routes.java](https://github.com/awangdev/LintCode/blob/master/Java/Bus%20Routes.java)|Hard|Java|[BFS]||
|477|[Sliding Puzzle.java](https://github.com/awangdev/LintCode/blob/master/Java/Sliding%20Puzzle.java)|Hard|Java|[BFS, Graph]||
|478|[Isomorphic Strings.java](https://github.com/awangdev/LintCode/blob/master/Java/Isomorphic%20Strings.java)|Easy|Java|[Hash Table]||
|479|[Cracking the Safe.java](https://github.com/awangdev/LintCode/blob/master/Java/Cracking%20the%20Safe.java)|Hard|Java|[DFS, Greedy, Math]||
|480|[Redundant Connection.java](https://github.com/awangdev/LintCode/blob/master/Java/Redundant%20Connection.java)|Medium|Java|[BFS, DFS, Graph, Tree, Union Find]||
|481|[Graph Valid Tree.java](https://github.com/awangdev/LintCode/blob/master/Java/Graph%20Valid%20Tree.java)|Medium|Java|[BFS, DFS, Graph, Union Find]||
|482|[Redundant Connection II.java](https://github.com/awangdev/LintCode/blob/master/Java/Redundant%20Connection%20II.java)|Hard|Java|[DFS, Graph, Tree, Union Find]||
|483|[The Maze.java](https://github.com/awangdev/LintCode/blob/master/Java/The%20Maze.java)|Medium|Java|[BFS, DFS]||
|484|[The Maze II.java](https://github.com/awangdev/LintCode/blob/master/Java/The%20Maze%20II.java)|Medium|Java|[BFS, DFS, PriorityQueue]||
|485|[The Maze III.java](https://github.com/awangdev/LintCode/blob/master/Java/The%20Maze%20III.java)|Hard|Java|[BFS, DFS, PriorityQueue]||
|486|[Predict the Winner.java](https://github.com/awangdev/LintCode/blob/master/Java/Predict%20the%20Winner.java)|Medium|Java|[DP, MiniMax]||
|487|[Next Greater Element I.java](https://github.com/awangdev/LintCode/blob/master/Java/Next%20Greater%20Element%20I.java)|Easy|Java|[Hash Table, Stack]||
|488|[Group Shifted Strings.java](https://github.com/awangdev/LintCode/blob/master/Java/Group%20Shifted%20Strings.java)|Medium|Java|[Hash Table, String]||
|489|[Delete Digits.java](https://github.com/awangdev/LintCode/blob/master/Java/Delete%20Digits.java)|Medium|Java|[Greedy, Priority Queue]||
|490|[Flatten 2D Vector.java](https://github.com/awangdev/LintCode/blob/master/Java/Flatten%202D%20Vector.java)|Medium|Java|[Design]||
|491|[The Spiral Matrix II.java](https://github.com/awangdev/LintCode/blob/master/Java/The%20Spiral%20Matrix%20II.java)|Medium|Java|[Array]||
|492|[Regular Expression Matching.java](https://github.com/awangdev/LintCode/blob/master/Java/Regular%20Expression%20Matching.java)|Hard|Java|[Backtracking, DP, Double Sequence DP, Sequence DP, String]||
|493|[Wildcard Matching.java](https://github.com/awangdev/LintCode/blob/master/Java/Wildcard%20Matching.java)|Hard|Java|[Backtracking, DP, Double Sequence DP, Greedy, Sequence DP, String]||
|494|[Robot Room Cleaner.java](https://github.com/awangdev/LintCode/blob/master/Java/Robot%20Room%20Cleaner.java)|Hard|Java|[Backtracking, DFS]||
|495|[Maximum Vacation Days.java](https://github.com/awangdev/LintCode/blob/master/Java/Maximum%20Vacation%20Days.java)|Hard|Java|[DP]||