package main

/*
 * Quick sort - https://en.wikipedia.org/wiki/Quicksort
 */

import "math/rand"

func quick_sort(arr []int) []int {
    
    if len(arr) <= 1 {
        return arr
    }
 
    median := arr[rand.Intn(len(arr))]
    
    low_part := make([]int, 0, len(arr))
    high_part := make([]int, 0, len(arr))
    middle_part := make([]int, 0, len(arr))
 
    for _, item := range arr {
        switch {
        case item < median:
            low_part = append(low_part, item)
        case item == median:
            middle_part = append(middle_part, item)
        case item > median:
            high_part = append(high_part, item)
        }
    }
 
    low_part = quick_sort(low_part)
    high_part = quick_sort(high_part)

    low_part = append(low_part, middle_part...)
    low_part = append(low_part, high_part...)
 
    return low_part
}

//func main() {
//    arr := utils.RandArray(10)
//    fmt.Println("Initial array is:", arr)
//    fmt.Println("")
//    fmt.Println("Sorted array is: ", quick_sort(arr))
//}