Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).
For example, this binary tree [1,2,2,3,4,4,3] is symmetric:
But the following [1,2,2,null,3,null,3] is not:
Recursively Solution:
/**
* 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:
bool isSame(TreeNode* t1, TreeNode* t2){
if(NULL == t1 && NULL == t2) return true;
else if(NULL == t1 && NULL != t2) return false;
else if(NULL != t1 && NULL == t2) return false;
else return t1->val == t2->val && isSame(t1->left, t2->right) && isSame(t1->right, t2->left);
}
bool isSymmetric(TreeNode* root) {
if(NULL == root) return true;
return isSame(root->left, root->right);
}
};
