Thread: Array sort with qsort, by using two criteria?

Hello!

I already posted one question related to my quick sort problem, but since it is solved and I have a new one, I am starting a new thread. So I try to sort an array with qsort and then save the new order, so this means if I have a list like:

4 3 7 2
[0] [1] [2] [3],

after sorting it becomes:

2 3 4 7
[3] [1] [0] [2] <== this is what I want to have!


Which works fine, with following code:

Code:

void qsort_my(int *a, int l, int r, int *array_order) {
   int j;
   if( l < r ) {
        j = split( a, l, r, array_order);
       qsort_my( a, l, j-1, array_order);
       qsort_my( a, j+1, r, array_order);
   }    
}
int split(int *a, int l, int r, int *array_order) {
   
   int pivot, i, j, t;
   pivot = a[l];
   i = l; j = r+1;

   int switch_pos_temp;
    while (1) {
        do ++i; while (a[i] >= pivot && i < r);
        do --j; while (a[j] < pivot);

        if (i >= j) break;
            switch_pos(&a[i], &a[j]);
            switch_pos(&array_order[i], &array_order[j]);
    } 
    switch_pos(&a[l], &a[j]);
    switch_pos(&array_order[l], &array_order[j]); 
   return j;
}

void switch_pos(int *one, int *two) {
    int temp = *one;
    *one = *two;
    *two = temp;
}

Code:

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

int main(int argc, char** argv) {

    int tot = 10;   int ini;
    int*list;
    list = malloc(sizeof(int)*tot);

    list[0] = 4;list[1] = 8; list[2] = 14; list[3] = 1; list[4] = 2;
    list[5] = 1;list[6] = 22; list[7] = 12; list[8] = 2; list[9] = 14;

    int *array_ordered; 
    array_ordered = malloc(sizeof(int)*tot);
    for(ini = 0; ini < tot; ini++) array_ordered[ini] = ini;
    qsort_my(list, 0, tot-1, array_ordered);

   free(list); free(array_ordered);
    return 0;
}

But now I would like to add the second criteria: if two numbers of my list are equal, then I want the them to be sorted according to their position in array_ordered, which means if I have:

9 9
[0] [5]

They stay the same, but if they are like:

9 9
[5] [0]

i would like to swap them (for some reasons..doesnt matter why).

I tried to add the criteria : (if (a[i] != a[j] || (a[i] == a[j] && array_order[i] > array_order[j]))) before calling switch_pos, but it is not working since sometimes you swap two numbers like:

11 9 15 9 <= here the 11 and 15 are swapped,

but the two 9's will never be swapped <=> compared.

Does someone have some suggestion how could I do this?? I mean I could run it again with the array_order on the first parameter position, but this would increase my runtime enormously!