Maximum Depth of N-ary Tree

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

Solution(javascript)

/**
 * // Definition for a Node.
 * function Node(val,children) {
 *    this.val = val;
 *    this.children = children;
 * };
 */
/**
 * @param {Node} root
 * @return {number}
 */
// iteration
const maxDepth = (root) => {
  let max = 0
  if (!root) {
    return 0
  }
  let frontier = [root]
  while (frontier.length) {
    const next = []
    max += 1
    frontier.forEach((node) => {
      next.push(...node.children)
    })
    frontier = next
  }
  return max
}