quick_sort

/*
 * File:   main.c
 * Author: Gerardo Cicalese
 *
 * Created on 16 settembre 2019, 15.48
 */

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

void print_vex(int * vex, int len){
    if(len<1)
        return;
    printf("%d ", *vex);
    print_vex(vex+1, len-1);
}

void swap_int(int * a, int * b){
    *a=*a+*b-(*b=*a);
}

int partition(int * a, int left, int right){
    int var=0, pivot=a[right]; /* pivot is last element */
    while(var<=right){
        if(a[var]<pivot){
            swap_int(a+var,a+left);
            ++var;
            ++left;
        }
        else if(a[var]>pivot){
            swap_int(a+var,a+right); /* we don't increase var cause we don't know */
            --right;               /* if the swapped element is smaller this time */
        }
        else
            ++var;
    }
    return left-1; /* indexes of elements with pivot value is [left-1; right] */
}

void quick_sort(int * vex, int left, int right){
    if( left >= right )
        return;
    int pivot=partition(vex, 0, right);
    quick_sort(vex, 0, pivot);
    quick_sort(vex, pivot+1, right);
}

int main(void){
    int array[10]={23, 62, 15, 97, 35, 78, 34, 89, 13, 57};
    quick_sort(array, 0, 9);
    print_vex(array, 10);
    return 0;
}