题解 | #二叉树的中序遍历# 递推法

di'tu

using System;
using System.Collections.Generic;

/*
public class TreeNode
{
	public int val;
	public TreeNode left;
	public TreeNode right;

	public TreeNode (int x)
	{
		val = x;
	}
}
*/

class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param root TreeNode类 
     * @return int整型一维数组
     */
    public List<int> inorderTraversal (TreeNode root) {
        List<int> res = new List<int>();
        if(root == null) return res;
        Inorder(root, res);
        return res;
    }
    public void Inorder(TreeNode root, List<int> res){
        if(root == null) return;
        Inorder(root.left, res);
        res.Add(root.val);
        Inorder(root.right, res);
        return;
    }
}