diff --git a/Week_01/zby/LeetCode_15.java b/Week_01/zby/LeetCode_15.java
new file mode 100644
index 0000000000000000000000000000000000000000..815a916dc3a3d8ee4df562fdf16c8693595b22af
--- /dev/null
+++ b/Week_01/zby/LeetCode_15.java
@@ -0,0 +1,142 @@
+package zby;
+
+import com.sun.javafx.binding.StringFormatter;
+
+import java.text.Format;
+import java.util.*;
+
+public class LeetCode_15 {
+
+    /**
+     * 15. 三数之和
+     * <p>
+     * 给你一个包含 n 个整数的数组 nums，判断 nums 中是否存在三个元素 a，b，c ，使得 a + b + c = 0 ？请你找出所有满足条件且不重复的三元组。
+     * <p>
+     * 注意：答案中不可以包含重复的三元组。
+     *
+     * @param args
+     */
+    public static void main(String[] args) {
+        LeetCode_15 code = new LeetCode_15();
+        int[] nums = {-1, 0, 1, 2, -1, -4};
+        List<List<Integer>> lists = code.threeSum3(nums);
+        System.out.println(lists);
+    }
+
+    /**
+     * 19 ms	41.2 MB
+     *
+     * @param nums
+     * @return
+     */
+    private List<List<Integer>> threeSum3(int[] nums) {
+        List result = new ArrayList<>(nums.length / 3);
+        Arrays.sort(nums);
+        int v, i, j;
+        for (int k = 0; k < nums.length; k++) {
+            if (nums[k] > 0) break;
+            if (k > 0 && nums[k] == nums[k - 1]) continue;
+            i = k + 1;
+            j = nums.length - 1;
+            while (i < j) {
+                v = nums[k] + nums[i] + nums[j];
+                if (v == 0) {
+                    result.add(new int[]{nums[k], nums[i++], nums[j--]});
+                    while (i < j && nums[i] == nums[i - 1]) i++;
+                    while (i < j && nums[j] == nums[j + 1]) j--;
+                } else if (v < 0) {
+                    i++;
+                } else {
+                    j--;
+                }
+            }
+        }
+        return result;
+    }
+
+    /**
+     * 18 ms	42.6 MB
+     *
+     * @param nums
+     * @return
+     */
+    private List<List<Integer>> threeSum2(int[] nums) {
+        List<List<Integer>> result = new ArrayList<>();
+        if (nums == null || nums.length == 0) return result;
+        Arrays.sort(nums);
+        for (int k = 0; k < nums.length; k++) {
+            if (nums[k] > 0) break;
+            if (k > 0 && nums[k] == nums[k - 1]) continue;
+            int i = k + 1, j = nums.length - 1;
+            int target = -nums[k];
+            while (i < j) {
+                if (nums[i] + nums[j] > target) j--;
+                else if (nums[i] + nums[j] < target) i++;
+                else {
+                    ArrayList<Integer> temp = new ArrayList<>();
+                    temp.add(nums[i]);
+                    temp.add(nums[j]);
+                    temp.add(nums[k]);
+                    result.add(temp);
+                    while (i < j && nums[i] == nums[i + 1]) i++;
+                    while (i < j && nums[j] == nums[j - 1]) j--;
+                    i++;
+                    j--;
+                }
+            }
+        }
+        return result;
+    }
+
+    /**
+     * 31 ms	42.4 MB
+     *
+     * @param nums
+     * @return
+     */
+    private List<List<Integer>> threeSum1(int[] nums) {
+        List<List<Integer>> result = new ArrayList<>();
+        Arrays.sort(nums);
+        for (int k = 0; k < nums.length - 2; k++) {
+            if (nums[k] > 0) break;
+            if (k > 0 && nums[k - 1] == nums[k]) continue;
+            int i = k + 1, j = nums.length - 1;
+            while (i < j) {
+                int s = nums[i] + nums[j] + nums[k];
+                if (s < 0) {
+                    while (i < j && nums[i] == nums[++i]) ;
+                } else if (s > 0) {
+                    while (i < j && nums[j] == nums[--j]) ;
+                } else {
+                    result.add(new ArrayList<>(Arrays.asList(nums[i], nums[j], nums[k])));
+                    while (i < j && nums[i] == nums[++i]) ;
+                    while (i < j && nums[j] == nums[--j]) ;
+                }
+            }
+        }
+        return result;
+    }
+
+
+    /**
+     * 超出时间限制	N/A	N/A
+     *
+     * @param nums
+     * @return
+     */
+    public List<List<Integer>> threeSum(int[] nums) {
+        Set<List<Integer>> result = new HashSet<>();
+        for (int i = 0; i < nums.length - 2; i++) {
+            for (int j = i + 1; j < nums.length - 1; j++) {
+                for (int k = j + 1; k < nums.length; k++) {
+                    if (nums[i] + nums[j] + nums[k] == 0) {
+                        ArrayList<Integer> list = new ArrayList<>(Arrays.asList(nums[i], nums[j], nums[k]));
+                        Collections.sort(list);
+                        result.add(list);
+                    }
+                }
+            }
+        }
+        return new ArrayList<>(result);
+    }
+}
diff --git a/Week_01/zby/LeetCode_70.java b/Week_01/zby/LeetCode_70.java
new file mode 100644
index 0000000000000000000000000000000000000000..68c5a415ee4b046eafa974cc7d44d3dd58b44782
--- /dev/null
+++ b/Week_01/zby/LeetCode_70.java
@@ -0,0 +1,82 @@
+package zby;
+
+import javax.sound.midi.Soundbank;
+
+public class LeetCode_70 {
+
+    /**
+     * 70. 爬楼梯
+     * 假设你正在爬楼梯。需要 n 阶你才能到达楼顶。
+     * <p>
+     * 每次你可以爬 1 或 2 个台阶。你有多少种不同的方法可以爬到楼顶呢？
+     * <p>
+     * 注意：给定 n 是一个正整数。
+     *
+     * @param args
+     */
+    public static void main(String[] args) {
+        LeetCode_70 code = new LeetCode_70();
+
+        long s = System.currentTimeMillis();
+        System.out.println(code.climbStairs2(50));
+        long e = System.currentTimeMillis() - s;
+        System.out.println(e);
+    }
+
+
+    /**
+     * 超出时间限制	N/A	N/A
+     *
+     * @param n
+     * @return
+     */
+    public int climbStairs(int n) {
+        if (n < 2) {
+            return 1;
+        }
+        return climbStairs(n - 1) + climbStairs(n - 2);
+    }
+
+
+    /**
+     * 0 ms	34.9 MB
+     *
+     * @param n
+     * @return
+     */
+    public int climbStairs1(int n) {
+        arr = new int[n];
+        return clim(n);
+    }
+
+    private int[] arr;
+
+    private int clim(int n) {
+        if (n < 2) {
+            return 1;
+        }
+        int t = arr[n - 1];
+        if (t == 0) {
+            t = clim(n - 1) + clim(n - 2);
+            arr[n - 1] = t;
+        }
+        return t;
+    }
+
+    /**
+     * 0 ms	34.8 MB
+     *
+     * @param n
+     * @return
+     */
+    public int climbStairs2(int n) {
+        int p = 0, q = 0, r = 1;
+        for (int i = 1; i <= n; i++) {
+            p = q;
+            q = r;
+            r = p + q;
+        }
+        return r;
+    }
+
+}