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101_Symmetric_Tree.cpp
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101_Symmetric_Tree.cpp
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/*
101. Symmetric Tree
Given the root of a binary tree, check whether it is a mirror of itself (i.e., symmetric around its center).
Example 1:
Input: root =[1,2,2,3,4,4,3]
Output: true
Example 2:
Input: root = [1,2,2,null,3,null,3]
Output: false
Constraints:
The number of nodes in the tree is in the range [1, 1000].
-100 <= Node.val <= 100
*/
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
private:
bool isMirror(TreeNode* r1,TreeNode*r2){
if(!r1 && !r2) return 1;
if(!r1 || !r2) return 0;
return (r1->val==r2->val &&isMirror(r1->left,r2->right) && isMirror(r1->right,r2->left) );
}
public:
bool isSymmetric(TreeNode* root) {
if(!root) return 1;
return isMirror(root->left,root->right);
}
};