94. Binary Tree Inorder Traversal

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

Binary Tree Inorder Traversal - LeetCode

 

이진 트리를 input으로 받아 중위 순회로 vector에 값을 채워 반환하는 문제.

중위 순회는 left, root, right순으로 방문하는 방법이다.

 

/**
 * 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:
    void inorderTraversal(vector<int>& nums, TreeNode* node)
    {
        if (node == nullptr) {
            return;
        }
        
        if (node->left != nullptr) {
            inorderTraversal(nums, node->left);
        }
        
        nums.push_back(node->val);
        
        if (node->right != nullptr) {
            inorderTraversal(nums, node->right);
        }
    }
    
    vector<int> inorderTraversal(TreeNode* root) {
        vector<int> ret;
        inorderTraversal(ret, root);
        return ret;
    }
};