Problem link [leetcode.com]
I don't know what to write so here's my recently accepted Leetcode submission:

func monotoneIncreasingDigits(n int) int {
⠀⠀⠀mult := 1
⠀⠀⠀result := 0
⠀⠀⠀next := math.MaxInt32
⠀⠀⠀
⠀⠀⠀for n > 0 {
⠀⠀⠀⠀⠀⠀curr := n % 10
⠀⠀⠀⠀⠀⠀multiple := mult * curr
⠀
⠀⠀⠀⠀⠀⠀if curr > next {
⠀⠀⠀⠀⠀⠀⠀⠀⠀result = multiple - 1
⠀⠀⠀⠀⠀⠀⠀⠀⠀next = result / mult
⠀⠀⠀⠀⠀⠀} else {
⠀⠀⠀⠀⠀⠀⠀⠀⠀result = multiple + result
⠀⠀⠀⠀⠀⠀⠀⠀⠀next = curr
⠀⠀⠀⠀⠀⠀}
⠀
⠀⠀⠀⠀⠀⠀mult *= 10
⠀⠀⠀⠀⠀⠀n /= 10
⠀⠀⠀}

⠀⠀⠀return result
}