Invert Binary Tree

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

Invert a binary tree.

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

给出一棵二叉树，求这棵二叉树的镜像。

搬运九章上的实现 ​​http://www.jiuzhang.com/solutions/invert-binary-tree/?source=zhmhw​​

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
struct TreeNode* invertTree(struct TreeNode* root) {
    if(root == 0)
        return  NULL;

    struct TreeNode *left = root->left;
    struct TreeNode *right = root->right;

    root->left = right;
    root->right = left;
    if(root->left != NULL)
        invertTree(root->left);
    if(root->right != NULL)
        invertTree(root->right);
    return root;
}