LC-305C

// 输入：pattern = "IIIDIDDD"
// 输出："123549876"
func smallestNumber(pat string) ( string) {
	// 升用最小的升, 降用最小的降
	n := len(pat)
	ans := strings.Builder{}
	q := []byte{'1', '2', '3', '4', '5', '6', '7', '8', '9'}
	for i := 0; i < n; i++ {
		c := pat[i]
		if c == 'I' {
			ans.WriteByte(q[0])
			q = q[1:]
		} else {
			cnt := 1
			j := i
			for ; j < n-1 && pat[j] == pat[j+1]; j++ { cnt++ }
			for t := cnt; t > 0; t-- {
				ans.WriteByte(q[0+t])
			}
			q = append(append([]byte{}, q[0]), q[cnt+1:]...)
			i = j
		}
	}
	ans.WriteByte(q[0])
	return ans.String()
}

func min(x, y int) int {
	if x < y { return x } else { return y }
}