Algoritmo quicksort en C

quicksort.c

#include <stdio.h>
#define MAX_NUM 50

void quicksort(int* const a, int begin, int end) 
{
	int i, j, medium, aux;
	int pivote;
	
	medium = (begin + end) / 2;
	pivote = a[medium];
	i = begin;
	j = end;
	do
	{
		while (a[i] < pivote) i++;
		while (a[j] > pivote) j--;
		if (i <= j)
		{
			aux = a[i];
			a[i] = a[j];
			a[j] = aux;
			i++;
			j--;
		}
	} while (i <= j);

	if (begin < j)
		quicksort(a, begin, j);
	if (i < end)
		quicksort(a, i, end);
}

int main(void)
{
	srand(time(NULL));
	int num[MAX_NUM];
	for(int i = 0; i != MAX_NUM; ++i)
		num[i] = rand() % 100;
	quicksort(num, 0, MAX_NUM-1);
	for(int i = 0; i != MAX_NUM; ++i)
		printf("%d\n", num[i]);
	getchar();
	return 0;
}