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/*
 * Name: qsort.c
 * Description: C implementation of the quicksort algorithm
 * Author: kyscg
 */

#include <stdio.h>

#define N 10

int split(int a[], int low, int high);
void quicksort(int a[], int low, int high);

int main(void)
{
    int a[N], i;

    printf("Enter %d numbers to be sorted: ", N);
    for (i = 0; i < N; i++)
        scanf("%d", &a[i]);

    quicksort(a, 0, N - 1);

    printf("In sorted order: ");
    for (i = 0; i < N; i++)
        printf("%d ", a[i]);

    printf("\n");
    return 0;
}

int split(int a[], int low, int high)
{
    int part_element = a[low];

    for (;;)
    {
        while (low < high && part_element <= a[high])
            high--;
        if (low >= high)
            break;
        a[low++] = a[high];

        while (low < high && a[low] <= part_element)
            low++;
        if (low >= high)
            break;
        a[high--] = a[low];
    }

    a[high] = part_element;
    return high;
}

void quicksort(int a[], int low, int high)
{
    int middle;

    if (low >= high)
        return;

    middle = split(a, low, high);
    quicksort(a, low, middle - 1);
    quicksort(a, middle + 1, high);
}