LeetCode in Kotlin
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(var `val`: Int) {
* var neighbors: List<Node?> = listOf()
* }
*/
class Solution {
private var max = 0
fun maxDepth(root: Node?): Int {
if (root == null) {
return 0
}
if (root.neighbors.isEmpty()) {
return 1
}
for (child in root.neighbors) {
findDepth(child, 1)
}
return max
}
private fun findDepth(n: Node?, d: Int) {
if (n!!.neighbors.isNotEmpty()) {
for (no in n.neighbors) {
findDepth(no, d + 1)
}
} else {
max = Math.max(max, d + 1)
}
}
}