package sum

func Sum(numbers []int) int {
	sum := 0

	for _, number := range numbers {
		sum += number
	}
	return sum
}

func SumAll(numbersToSum ...[]int) []int {
	res := make([]int, len(numbersToSum))

	for i, numbers := range numbersToSum {
		res[i] = Sum(numbers)
	}

	return res
}

func SumAllTails(numbersToSum ...[]int) []int {
	res := make([]int, len(numbersToSum))

	for i, numbers := range numbersToSum {
		if len(numbers) == 0 {
			res[i] = 0
			continue
		}
		res[i] = Sum(numbers[1:])
	}

	return res
}