c.sample

#include <stdio.h>

#define ARR_LEN 7

void qsort(int v[], int left, int right);
void printArr(int v[], int len);

int main()
{
	int i;
	int v[ARR_LEN] = { 4, 3, 1, 7, 9, 6, 2 };
	printArr(v, ARR_LEN);
	qsort(v, 0, ARR_LEN-1);
	printArr(v, ARR_LEN);
	return 0;
}

void qsort(int v[], int left, int right)
{
	int i, last;
	void swap(int v[], int i, int j);

	if (left >= right)
		return;
	swap(v, left, (left + right) / 2);
	last = left;
	for (i = left+1; i <= right; i++)
		if (v[i] < v[left])
			swap(v, ++last, i);
	swap(v, left, last);
	qsort(v, left, last-1);
	qsort(v, last+1, right);
}

void swap(int v[], int i, int j)
{
	int temp;

	temp = v[i];
	v[i] = v[j];
	v[j] = temp;
}

void printArr(int v[], int len)
{
	int i;
	for (i = 0; i < len; i++)
		printf("%d ", v[i]);
	printf("\n");
}

// From https://github.com/Heatwave/The-C-Programming-Language-2nd-Edition/blob/master/chapter-4-functions-and-program-structure/8.qsort.c