Permations of an array in Go

permutations.go

func Pow(x, n int) int {
	return int(math.Pow(float64(x), float64(n)))
}

func Permutations(array []int) [][]int {
	size := len(array)
	total := Pow(2, size)
	permutations := make([][]int, 0, total)

	for i := 0; i < total; i++ {
		permutation := make([]int, 0, size)
		for j := 0; j < size; j++ {
			if Pow(2, j)&i != 0 {
				permutation = append(permutation, array[j])
			}
		}
		permutations = append(permutations, permutation)
	}

	return permutations
}

permutations_example.go

array := []int{1, 2, 3}
permutations := Permutations(array)
for _, p := range permutations {
	fmt.Println(p)
}

permutations_output_example.txt

[]
[1]
[2]
[1 2]
[3]
[1 3]
[2 3]
[1 2 3]