Question

559. Maximum Depth of N-ary Tree

中文文档

Description

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.

Solutions

Solution 1

"""
# Definition for a Node.
class Node:
  def __init__(self, val=None, children=None):
    self.val = val
    self.children = children
"""


class Solution:
  def maxDepth(self, root: 'Node') -> int:
    if root is None:
      return 0
    return 1 + max([self.maxDepth(child) for child in root.children], default=0)

/*
// 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 ans = 1;
    for (Node child : root.children) {
      ans = Math.max(ans, 1 + maxDepth(child));
    }
    return ans;
  }
}

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

  Node() {}

  Node(int _val) {
    val = _val;
  }

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

class Solution {
public:
  int maxDepth(Node* root) {
    if (!root) return 0;
    int ans = 1;
    for (auto& child : root->children) ans = max(ans, 1 + maxDepth(child));
    return ans;
  }
};

/**
 * Definition for a Node.
 * type Node struct {
 *   Val int
 *   Children []*Node
 * }
 */

func maxDepth(root *Node) int {
  if root == nil {
    return 0
  }
  ans := 1
  for _, child := range root.Children {
    ans = max(ans, 1+maxDepth(child))
  }
  return ans
}