[LeetCode] 559. Maximum Depth of N-ary Tree

 1 /*
 2 // Definition for a Node.
 3 class Node {
 4     public int val;
 5     public List<Node> children;
 6 
 7     public Node() {}
 8 
 9     public Node(int _val,List<Node> _children) {
10         val = _val;
11         children = _children;
12     }
13 };
14 */
15 class Solution {
16     public int maxDepth(Node root) {
17         if (root == null) {
18             return 0;
19         }
20         int max = 0;
21         for(Node child : root.children) {
22             max = Math.max(maxDepth(child), max);
23         }
24         return max + 1;
25     }
26 }

 1 class Solution {
 2     public int maxDepth(Node root) {
 3         if(root == null) {
 4             return 0;
 5         }
 6         int level = 0;
 7         int currLevelCount = 1;
 8         int nextLevelCount = 0;
 9         Queue<Node> queue = new LinkedList<>();
10         queue.add(root);
11         while(!queue.isEmpty()) {
12             Node currNode = queue.poll();
13             currLevelCount--;
14             for(Node child : currNode.children) {
15                 queue.add(child);
16                 nextLevelCount++;
17             }            
18             if(currLevelCount == 0) {
19                 level++;
20                 currLevelCount = nextLevelCount;
21                 nextLevelCount = 0;
22             }
23         }
24         return level;
25     }
26 }