func swap(sw []int) { for a, b := 0, len(sw)-1; a < b; a, b = a+1, b-1 { sw[a], sw[b] = sw[b], sw[a] } }
func main() { x := []int{3, 2, 1} swap(x) fmt.Println(x) // Output: [1 2 3] }
