func exclusiveTime(n int, logs []string) []int {
	res := make([]int, n)
	if len(logs) == 0 {
		return res
	}
	pre := -1 // All func start from 0.
	st := []int{0}
	for i := range logs {
		log := strings.Split(logs[i], ":")
		id, _ := strconv.Atoi(log[0])
		cur, _ := strconv.Atoi(log[2])
		res[id]++
		if log[1] == "start" {
			res[st[len(st)-1]] += cur - pre - 1
			st = append(st, id)
		} else {
			res[id] += cur - pre - 1
			st = st[:len(st)-1]
		}
		pre = cur
	}
	return res
}