[LeetCode/easy] Symmentric-Tree (C++)

leetcode.com/problems/symmetric-tree/

Symmetric Tree - LeetCode

재귀를 이용하여 각각 루트노드에서 왼쪽 노드와 오른쪽 노드 값이 같은지 비교합니다.

 

/**
 * 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 R(TreeNode* leftNode, TreeNode* rightNode) {
        if(leftNode == NULL && rightNode == NULL) return true;
        if(leftNode == NULL || rightNode == NULL) return false;
        if(leftNode -> val != rightNode -> val) return false;
        return R(leftNode -> left, rightNode -> right) && R(leftNode -> right, rightNode -> left);
    }
    
    bool isSymmetric(TreeNode* root) {
        if(root == NULL) return true;
        return R(root -> left, root -> right);
    }
};