LeetCode-in-Java
559. Maximum Depth of N-ary Tree
Easy
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.
Nary-Tree input serialization is represented in their level order traversal, each group of children is separated by the null value (See examples).
Example 1:
Input: root = [1,null,3,2,4,null,5,6]
Output: 3
Example 2:
Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
Output: 5
Constraints:
- The total number of nodes is in the range
[0, 104]. - The depth of the n-ary tree is less than or equal to
1000.
Solution
import com_github_leetcode.Node;
/*
// Definition for a Node.
class Node {
public int val;
public List<Node> neighbors;
public Node() {}
public Node(int _val) {
val = _val;
}
public Node(int _val, List<Node> _neighbors) {
val = _val;
children = _neighbors;
}
};
*/
public class Solution {
private int max = 0;
public int maxDepth(Node root) {
if (root == null) {
return 0;
}
if (root.neighbors == null || root.neighbors.isEmpty()) {
return 1;
}
for (Node child : root.neighbors) {
findDepth(child, 1);
}
return max;
}
private void findDepth(Node n, int d) {
if (n.neighbors != null && !n.neighbors.isEmpty()) {
for (Node no : n.neighbors) {
findDepth(no, d + 1);
}
} else {
max = Math.max(max, d + 1);
}
}
}