LintCode - 175.翻转二叉树

翻转一棵二叉树

您在真实的面试中是否遇到过这个题？ 

Yes

样例

  1         1
 / \       / \
2   3  => 3   2
   /       \
  4         4

/**
 * Definition of TreeNode:
 * class TreeNode {
 * public:
 *     int val;
 *     TreeNode *left, *right;
 *     TreeNode(int val) {
 *         this->val = val;
 *         this->left = this->right = NULL;
 *     }
 * }
 */
class Solution {
public:
    /**
     * @param root: a TreeNode, the root of the binary tree
     * @return: nothing
     */
    void invertBinaryTree(TreeNode *root) {
        // write your code here
        if( root == NULL ) return;
        
        TreeNode* node = root->left;
        root->left = root->right;
        root->right = node;
        
        invertBinaryTree( root->left );
        invertBinaryTree( root->right );
    }
};