/*
 * @lc app=leetcode.cn id=226 lang=java
 *
 * [226] 翻转二叉树
 */

// @lc code=start
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 * int val;
 * TreeNode left;
 * TreeNode right;
 * TreeNode() {}
 * TreeNode(int val) { this.val = val; }
 * TreeNode(int val, TreeNode left, TreeNode right) {
 * this.val = val;
 * this.left = left;
 * this.right = right;
 * }
 * }
 */
class InvertTree {
  public TreeNode invertTree(TreeNode root) {
    if (root == null) {
      return null;
    }
    if (root.left == null && root.right == null) {
      return root;
    }
    TreeNode temp = root.left;
    root.left = root.right;
    root.right = temp;
    invertTree(root.left);
    invertTree(root.right);
    return root;
  }
}
// @lc code=end