#include <stdio.h>
#include <stdlib.h>

void swap(int* x, int* y);
void qsort(int A[], int left, int right);
int partition(int A[], int left, int right);


int main(int argc, char *argv[]){
    int A[8] = {7, 2, 1, 6, 8, 5, 3, 4};
    qsort(A,0,7);
}

void qsort(int A[], int left, int right){

    if (left>=right){
        return;
    }

    int p;
    p = partition(A, left, right);

    qsort(A, left, p-1);
    qsort(A, p+1, right);
}

int partition(int A[], int left, int right){
    int lm, rm;
    lm = left+1;
    rm = right;

    while(lm<=rm){

        while(A[lm] < A[left]){
            lm++;
        }

        while(A[rm] > A[left]){
            rm--;
        }

        if(lm<=rm){
            swap(&A[lm], &A[rm]);
        }
    }
    swap(&A[rm], &A[left]);
    return rm;
}

void swap(int* x, int* y){
    int temp;

    temp = *x;
    *x = *y;
    *y = temp;
}