leetcode 226. 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

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    TreeNode* invertTree(TreeNode* root)     {        if (!root || (!root->left && !root->right))            return root;                TreeNode *temp = root->left;        root->left = root->right;        root->right = temp;                invertTree(root->left);        invertTree(root->right);        return root;    }};