LeetCode 101. Symmetric Tree

 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 {
	public:
	bool isMirror(TreeNode* x, TreeNode* y){
	if(!x and !y) return true;
	if(!x or !y) return false;
	return (x->val == y->val) and
	isMirror(x->left, y->right) and
	isMirror(y->left, x->right);
	}
	bool isSymmetric(TreeNode* root) {
	if(!root)
	return true;
	return isMirror(root->left, root->right);
	}
	};

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