quickSort

/*
 * File:   main.c
 * Author: Gerardo Cicalese
 *
 * Created on 18 novembre 2019, 14.22
 */

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

typedef char Info;

void quickSort(Info *, int);
int partition(Info *, int);
void swap(Info *, Info *);
int compare(Info, Info);

int main(void)
{
    srand(time(NULL));
    Info array[10];

    for(int i=0; i<10; ++i)
        array[i] = 'a' + rand()%('z' - 'a' + 1);

    quickSort(array, 10);

    for(int i=0; i<10; ++i)
        printf("%c\t", array[i]);

    return 0;
}

void quickSort(Info * array, int len)
{
    if(len <= 1)
        return;

    int pivot = partition(array, len);
    quickSort(array, pivot);
    quickSort(array+pivot+1, len-pivot-1);
}

int partition(Info * array, int len)
{
    int i = 1, j = 1;

    for(; i < len; ++i)
        if(-1 == compare(array[i], array[0]))
            swap(array+i, array+j++);

    swap(array, array+j-1);
    return j-1;
}

void swap(Info * a, Info * b)
{
    Info temp = *a;
    *a = *b;
    *b = temp;
}

int compare(Info a, Info b)
{
    if(a == b)
        return 0;

    if(a > b)
        return 1;

    return -1;
}