Invert a binary tree.
4 / \ 2 7 / \ / \ 1 3 6 9to
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) {
invert(root);
return root;
}
void invert(TreeNode* root){
if(root == NULL || (root->left == NULL&&root->right == NULL))
return;
TreeNode *temp = root->left;
root->left = root->right;
root->right = temp;
invert(root->left);
invert(root->right);
}
};