[LeetCode 226] Invert Binary Tree

Invert a binary tree.

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

to

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

递归的方法：

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

非递归的方法：

lass Solution {public:TreeNode* invertTree(TreeNode* root) {queue<TreeNode*> tree_ueue;if(root == NULL)return root;tree_queue.push(root);while(!ree_queue.empty()){TreeNode* pNode = tree_queue.front();tree_queue.pop();TreeNode* pTmp = pNode->left;pNode->left = pNode->right;pNode->right = pTmp;if(pNode->left)tree_queue.push(pNode->left);if(pNode ->right)tree_queue.push(pNode->right);}return root;}};