sem4-problem3-qsort

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#define MAX_ARR_SIZE 3000
#define MAX_STR_LEN 100

char a[MAX_ARR_SIZE][MAX_STR_LEN],
        b[MAX_ARR_SIZE][MAX_STR_LEN];

void qSort(int l, int r)
{
    if (r - l < 2)
        return;

    int m = rand() % (r - l) + l;
    int ll = l, rr = r - 1, i;

    for (i = l; i < r; i++)
        if (strcmp(a[i], a[m]) < 0)
            strcpy(b[ll++], a[i]);
        else if (strcmp(a[i], a[m]) > 0)
            strcpy(b[rr--], a[i]);

    for (i = ll; i <= rr; i++)
        strcpy(b[i], a[m]);

    for (i = l; i < r; i++)
        strcpy(a[i], b[i]);

    qSort(l, ll);
    qSort(rr + 1, r);
}

int main(int argc, char const *argv[])
{
    srand(time(NULL));

    int i, n;
    printf("Number of lines to sort: ");
    scanf("%d", &n);
    for (i = 0; i < n; i++)
        scanf("%s", a[i]);

    qSort(0, n);

    printf("\n");
    for (i = 0; i < n; i++)
        printf("%s\n", a[i]);

    return 0;
}