Problem
Given a binary tree, check whether it is a mirror of itself (ie, symmetric around its center).
Example
For example, this binary tree [1,2,2,3,4,4,3] is symmetric:
1
/ \
2 2
/ \ / \
3 4 4 3
But the following [1,2,2,null,3,null,3] is not:
1
/ \
2 2
\ \
3 3
Code
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
static int var = [](){
std::ios::sync_with_stdio(false);
cin.tie(NULL);
return 0;
}();
class Solution {
public:
bool isSymmetric(TreeNode* root) {
if(root==NULL)
return true;
else
return Symmetric(root->left,root->right);
}
bool Symmetric(TreeNode* left,TreeNode* right){
if(left==NULL || right==NULL){
return left==right;
}
else{
return (left->val==right->val) && Symmetric(left->left,right->right) && Symmetric(left->right,right->left);
}
}
};
Result
101. Symmetric Tree.png
