[leetcode oj 226]Invert Binary Tree

Invert a binary tree.

4
/ \
2 7
/ \ / \
1 3 6 9
to
4
/ \
7 2
/ \ / \
9 6 3 1
反转二叉树思密达，就是左儿子变右儿子右儿子变左儿子，那么第一个想法是递归。

/**
 * 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 == NULL)
            return NULL;
        TreeNode *tmp = root->left;;
        root->left = invertTree(root->right);
        root->right = invertTree(tmp);
        return root;
    }
};

that’s it