LeetCode in Kotlin
264. Ugly Number II
Medium
An ugly number is a positive integer whose prime factors are limited to 2, 3, and 5.
Given an integer n, return the nth ugly number.
Example 1:
Input: n = 10
Output: 12
Explanation: [1, 2, 3, 4, 5, 6, 8, 9, 10, 12] is the sequence of the first 10 ugly numbers.
Example 2:
Input: n = 1
Output: 1
Explanation: 1 has no prime factors, therefore all of its prime factors are limited to 2, 3, and 5.
Constraints:
1 <= n <= 1690
Solution
class Solution {
fun nthUglyNumber(n: Int): Int {
val ugly = IntArray(n)
var i2 = 0
var i3 = 0
var i5 = 0
var ugly2 = 2
var ugly3 = 3
var ugly5 = 5
var nextugly: Int
ugly[0] = 1
for (i in 1 until n) {
nextugly = Math.min(Math.min(ugly2, ugly3), ugly5)
ugly[i] = nextugly
if (nextugly == ugly2) {
i2++
ugly2 = ugly[i2] * 2
}
if (nextugly == ugly3) {
i3++
ugly3 = ugly[i3] * 3
}
if (nextugly == ugly5) {
i5++
ugly5 = ugly[i5] * 5
}
}
return ugly[n - 1]
}
}