Invert a binary tree.
4 / 2 7 / \ / 1 3 6 9
to
4 / 7 2 / \ / 9 6 3 1
Trivia:
This problem was inspired by this original tweet by Max Howell:
Google: 90% of our engineers use the software you wrote (Homebrew), but you can’t invert a binary tree on a whiteboard so fuck off.
额， 这也不能怪Google，既然你这么吊，连这道题都做不出来就真的太不应该了。
(╯°□°)╯︵ ???? ???u?q
1 /** 2 * Definition for a binary tree node. 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8 * }; 9 */ 10 class Solution { 11 public: 12 TreeNode* invertTree(TreeNode* root) { 13 if (root == NULL) return NULL; 14 TreeNode *res = new TreeNode(root->val); 15 res->left = invertTree(root->right); 16 res->right = invertTree(root->left); 17 return res; 18 } 19 };
原文：http://www.cnblogs.com/easonliu/p/4571909.html