func quickSort(arr []int) []int { if len(arr) <= 1 { return arr } index := len(arr) / 2
var left, right []int for i, v := range arr { if i == index { continue } if v <= arr[index] { left = append(left, v) continue } right = append(right, v) } return append(append(quickSort(left), arr[index]), quickSort(right)...) }