LeetCode - 94. Binary Tree Inorder Traversal(Tree, Stack, DFS, Binary Tree)*

문제

Given the root of a binary tree, return the inorder traversal of its nodes' values.

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

Example 1:

Input: root = [1,null,2,3]
Output: [1,3,2]

Example 2:

Input: root = []
Output: []

Example 3:

Input: root = [1]
Output: [1]

풀이

 */
class Solution {
    List<Integer> res = new ArrayList<>();
    
    public List<Integer> inorderTraversal(TreeNode root) {
        
        inorder(root);

        return res;
    }

    public void inorder(TreeNode root){
        if(root==null) return;

        inorder(root.left);
        res.add(root.val);
        inorder(root.right);
    }
}