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LeetCode

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Problem

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:

img

Input: root = [1,null,3,2,4,null,5,6]
Output: 3

Example 2:

img

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 $[0, 10^4]$.
  • The depth of the n-ary tree is less than or equal to 1000.

Code

/*
// Definition for a Node.
class Node {
    public int val;
    public List<Node> children;

    public Node() {}

    public Node(int _val) {
        val = _val;
    }

    public Node(int _val, List<Node> _children) {
        val = _val;
        children = _children;
    }
};
*/

class Solution {
    public int maxDepth(Node root) {
        if (root == null) return 0;

        int maxHeight = 0;
        for (Node child : root.children) {
            maxHeight = Math.max(maxHeight, maxDepth(child));
        }

        return 1 + maxHeight;
    }
}