Leetcode skimming: binary tree 08 (maximum depth of n-ary tree)

559.n The maximum depth of the fork tree

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Given a n Fork tree , Find its maximum depth .

Maximum depth is the total number of nodes on the longest path from the root node to the farthest leaf node .

for example , Given a 3 Fork tree :

We should return to its maximum depth ,3.

It's the same , Sequence traversal is enough .

package com.programmercarl.tree;

import java.util.ArrayDeque;
import java.util.Deque;

/** * @ClassName MaxDepth2 * @Descriotion TODO * @Author nitaotao * @Date 2022/7/3 22:24 * @Version 1.0 * 559. N  The maximum depth of the fork tree  * https://leetcode.cn/problems/maximum-depth-of-n-ary-tree/ **/
public class MaxDepth2 {
    
    public int maxDepth(Node root) {
    
        int maxDepth = 0;
        if (root == null) {
    
            return maxDepth;
        }
        Deque<Node> deque = new ArrayDeque<Node>();
        // Traverse the current tree hierarchically , Depth of first floor +1
        deque.offer(root);
        while (!deque.isEmpty()) {
    
            // This sentence is the core , size It is a variable that controls how many elements there are in each layer 
            int size = deque.size();
            maxDepth++;
            while (size > 0) {
    
                root = deque.poll();
                for (Node item : root.children) {
    
                    deque.offer(item);
                }
                size--;
            }
        }
        return maxDepth;
    }
}