package LeetCode;

public class LeetCode226 {

/// 226. Invert Binary Tree

/// https://leetcode.com/problems/invert-binary-tree/description/

/// 时间复杂度: O(n), n为树中节点个数

/// 空间复杂度: O(h), h为树的高度

public class TreeNode {

int val;

TreeNode left;

TreeNode right;

TreeNode(int x) {

val = x;

}

}

public TreeNode invertTree(TreeNode root) {

if (root == null)

return null;

// 左边翻转，右边翻转

TreeNode left = invertTree(root.left);

TreeNode right = invertTree(root.right);

// 左右交换！

root.left = right;

root.right = left;

return root;

}

}