Symmetric Tree

problem

주어진 트리가 대칭인지 확인하는 문제입니다
https://leetcode.com/problems/symmetric-tree/

solution

/**
 * 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 isSymmetric(TreeNode* root) {
        TreeNode* left = root->left;
        TreeNode* right = root->right;
        
        vector<int> l;
        vector<int> r;
        
        leftTraversal(left, l);
        rightTraversal(right, r);
        
        if(l.size()!= r.size()) return false;
        //123 123
        int n = l.size();
        for(int i=0;i<n;i++){
            if(l[i] != r[i]){
                return false;
            }
        }
        
        return true;
    }
    void leftTraversal(TreeNode* root, vector<int>&L){
        if(root)
        {
            L.push_back(root->val);
            leftTraversal(root->left, L);
            leftTraversal(root->right, L);
        }else{
            L.push_back(101);
            return;
        }
    }
    void rightTraversal(TreeNode* root, vector<int>& R){
        if(root)
        {
            R.push_back(root->val);
            rightTraversal(root->right, R);
            rightTraversal(root->left, R);
        }else{
            R.push_back(101);
            return;
        }
    }
};