LeetCode in Kotlin
1104. Path In Zigzag Labelled Binary Tree
Medium
In an infinite binary tree where every node has two children, the nodes are labelled in row order.
In the odd numbered rows (ie., the first, third, fifth,…), the labelling is left to right, while in the even numbered rows (second, fourth, sixth,…), the labelling is right to left.
Given the label of a node in this tree, return the labels in the path from the root of the tree to the node with that label.
Example 1:
Input: label = 14
Output: [1,3,4,14]
Example 2:
Input: label = 26
Output: [1,2,6,10,26]
Constraints:
1 <= label <= 10^6
Solution
import java.util.LinkedList
@Suppress("NAME_SHADOWING")
class Solution {
fun pathInZigZagTree(label: Int): List<Int> {
var label = label
val answer: MutableList<Int> = LinkedList()
while (label != 0) {
answer.add(0, label)
val logNode = (Math.log(label.toDouble()) / Math.log(2.0)).toInt()
val levelStart = Math.pow(2.0, logNode.toDouble()).toInt()
val diff = label - levelStart
val d2 = diff / 2
val prevEnd = levelStart - 1
val prevLabel = prevEnd - d2
label = prevLabel
}
return answer
}
}