QUESTION:

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:

1. The depth of the tree is at most 1000.
2. The total number of nodes is at most 5000.

EXPLANATION:

其实也就是之前的层序遍历加上标记位置即可。

SOLUTION:

class Solution {
    int maxDepthResult = 1;

    public int maxDepth(Node root) {
        if(root==null) return 0;
        for(int i = 0;i<root.children.size();i++){
            maxDepthHelper(root.children.get(i),2);
        }
        return maxDepthResult;
    }

    public void maxDepthHelper(Node root,int dep){
        maxDepthResult = Math.max(maxDepthResult,dep);
        for(int i = 0;i<root.children.size();i++){
            maxDepthHelper(root.children.get(i),dep+1);
        }
    }
}