leetcode226. Invert Binary Tree

226. Invert Binary Tree

Invert a binary tree.

     4   /   \  2     7 / \   / \1   3 6   9

to

     4   /   \  7     2 / \   / \9   6 3   1

解法

递归进行二叉树的反转，直到结点为null。

/** * Definition for a binary tree node. * public class TreeNode { *     int val; *     TreeNode left; *     TreeNode right; *     TreeNode(int x) { val = x; } * } */public class Solution {    public TreeNode invertTree(TreeNode root) {        if (root == null) {            return root;        }        TreeNode temp = root.left;        root.left = root.right;        root.right = temp;        invertTree(root.left);        invertTree(root.right);        return root;    }}