Binary Tree Inorder Traversal

problem

Bst가 주어질때, inorder로 순회한 값을 리턴하는 문제입니다.
Input: root = [1,null,2,3]
Output: [1,3,2]

https://leetcode.com/problems/binary-tree-inorder-traversal/

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:
    vector<int> inorderTraversal(TreeNode* root) {
        vector<int> ans;
        inorderTraversal(root, ans);
        return ans;
        
    }
    void inorderTraversal(TreeNode* root, vector<int>& ans){
        if(root == nullptr) return;
        else{
            inorderTraversal(root->left, ans);
            ans.push_back(root->val);
            inorderTraversal(root->right, ans);
        }
    }
};

후기

전에 BST를 구현해 본 적이 있어서 쉽게 풀 수 있었습니다.