leetcode-go/medium/264.ugly-number-ii.go

func nthUglyNumber(n int) int {
	nums := []int{1}
	next2, next3, next5 := 2, 3, 5
	for i, i2, i3, i5 := 1, 0, 0, 0; i < n; i++ {
		next := next2
		if next3 < next {
			next = next3
		}
		if next5 < next {
			next = next5
		}
		nums = append(nums, next)
		if next == next2 {
			i2++
			next2 = nums[i2] * 2
		}
		if next == next3 {
			i3++
			next3 = nums[i3] * 3
		}
		if next == next5 {
			i5++
			next5 = nums[i5] * 5
		}
	}
	return nums[n-1]
}