[刷题防痴呆] 0559 - N叉树的最大深度 (Maximum

题目地址

https://leetcode.com/problems/maximum-depth-of-n-ary-tree/

题目描述

559. Maximum Depth of N-ary Tree

Given a n-ary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).

 

Example 1:



Input: root = [1,null,3,2,4,null,5,6]
Output: 3
Example 2:



Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
Output: 5

思路

• dfs.
• 一层层+1.

关键点

代码

• 语言支持：Java

/*
// Definition for a Node.
class Node {
    public int val;
    public List<Node> children;

    public Node() {}

    public Node(int _val) {
        val = _val;
    }

    public Node(int _val, List<Node> _children) {
        val = _val;
        children = _children;
    }
};
*/

class Solution {
    public int maxDepth(Node root) {
        if (root == null) {
            return 0;
        }
        int max = 0;
        for (Node node: root.children) {
            max = Math.max(max, maxDepth(node));
        }
        return max + 1;
    }
}