Leetcode56： Invert Binary Tree

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

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

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

/**
* 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) {
queue<TreeNode*> quetree;
if(root == NULL)
return NULL;
quetree.push(root);
while(!quetree.empty())
{
TreeNode* Node = quetree.front();
quetree.pop();
TreeNode* temp = Node->left;
Node->left = Node->right;
Node->right = temp;
if(Node->left != NULL)
quetree.push(Node->left);
if(Node->right != NULL)
quetree.push(Node->right);
}
return root;
}
};