Problem

Invert a binary tree.

Example

Input:

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

Output:

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

Code

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
static int var = [](){
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();
class Solution {
public:
    TreeNode* invertTree(TreeNode* root) {
        if(root==NULL)
            return NULL;
        TreeNode *temp = root->left;
        root->left = invertTree(root->right);
        root->right = invertTree(temp);
        return root;
    }
};

Result

226. Invert Binary Tree.png