LeetCode-Java-559. Maximum Depth of N-ary Tree

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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:


假装是个图


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.

图在这

代码

通过递归的思想，对子节点进行不同的处理

/*
// 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 {
    public int maxDepth(Node root) {
        if(root == null){
            return 0;
        }else{
            return deep(root,1);
        }
    }

    public static int deep(Node root ,int d){
        List<Node> childer = root.children;
        int size=childer==null?0:childer.size();
        if(size==0){
            return d;
        }else{
            int [] tag = new int[size];
            for(int i=0;i<size;i++){
                Node x = childer.get(i);
                tag[i] = deep(x,d+1);
            }
            int max = 0;
            for(int i=0;i<size;i++){
                if(tag[i]>tag[max]){
                    max = i;
                }
            }
            return tag[max];
        }
    }
}