The following go program is supposed to generate all permutations of a slice of integers:
package main
import "fmt"
func permute(nums []int) [][]int {
var res [][]int
var s []int
permuteHlp(&res, nums, 0, s)
return res
}
func permuteHlp(res *[][]int, nums []int, i int, s []int) {
if i == len(nums) {
*res = append(*res, s)
return
}
for j := i; j < len(nums); j++ {
s = append(s, nums[j])
nums[i], nums[j] = nums[j], nums[i]
permuteHlp(res, nums, i+1, s)
s = s[:len(s)-1]
nums[i], nums[j] = nums[j], nums[i]
}
}
func main() {
x := []int{1,2,3,4}
y := permute(x)
fmt.Println(y)
}
The output is unexpected
[[1 2 4 3] [1 2 4 3] [1 3 4 2] [1 3 4 2] [1 4 2 3] [1 4 2 3] [2 1 4 3] [2 1 4 3] [2 3 4 1] [2 3 4 1] [2 4 1 3] [2 4 1 3] [3 2 4 1] [3 2 4 1] [3 1 4 2] [3 1 4 2] [3 4 2 1] [3 4 2 1] [4 2 1 3] [4 2 1 3] [4 3 1 2] [4 3 1 2] [4 1 2 3] [4 1 2 3]]
I don't understand what is wrong here. I would appreciate any help. Thank you!