leetcode讲解--559. Maximum Depth of N-ary Tree

题目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.For example, given a 3-ary tree:We should return its max depth, which is 3.Note:The depth of the tree is at most 1000.The total number of nodes is at most 5000.题目地址讲解这道题需要对每次层的深度做个记录，我直接使用结点的val属性来记录深度。另外就是给根节点深度置为1的时候有个技巧，设置一个一次性的flag。Java代码/// Definition for a Node.class Node { public int val; public List<Node> children; public Node() {} public Node(int _val,List<Node> _children) { val = _val; children = _children; }};/class Solution { private int result=0; private boolean flag = true; public int maxDepth(Node root) { if(root==null){ return result; } if(flag){ root.val=1; flag = false; } if(result<root.val){ result = root.val; } for(Node node:root.children){ node.val = root.val+1; maxDepth(node); } return result; } }