퀵정렬

#include <stdio.h>
#include <stdlib.h>
void printArr(int *a, int start, int end)
{
    int i;
 
    for (i = start; i <= end; i++)
        printf("%3d", a[i]);
    printf("\n");
}
int partition(int a[], int p, int r)
{
    int i, j;
    int num;
 
    for (i = p, j = 0; i + j <= r;)
    {
        if (a[r] >= a[i + j])
        {
            num = a[i + j];
            a[i + j] = a[i];
            a[i] = num;
            i++;
        }
        else
            j++;
    }
 
    return i - 1;
}
void quickSort(int* a, int start, int end)
{
    int index = partition(a, start, end);
 
    if (index - 1 > start)
        quickSort(a, start, index-1);
    if (index + 1 < end)
        quickSort(a, index + 1, end);
 
    printArr(a, 0, 9);
}
int main(void)
{
    int a[] = { 10, 50, 69, 27, 40, 72, 59, 21, 96, 4 };
    int i;
 
    quickSort(a, 0, 9);
 
    printArr(a, 0, 9);
}

 

결과: