LeetCode: 559. Maximum Depth of N-ary Tree

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559. Maximum Depth of N-ary Tree

LeetCode - Maximum Depth of N-ary Tree

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 depth of the n-ary tree is less than or equal to 1000.
The total number of nodes is between [0, 10^4].

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public int maxDepth(Node root) {
  if (root == null) {
    return 0;
  }
  if (root.children == null || root.children.isEmpty()) {
    return 1;
  }
  int maxDepth = Integer.MIN_VALUE;
  for (Node child : root.children) {
    maxDepth = Math.max(maxDepth, maxDepth(child));
  }
  return maxDepth + 1;
}

static 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;
  }
}