source.c

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#include <stdio.h>
#include <stdlib.h>
 
 
//the  function below will compute the vector permutation p
//which returns a list of the index of elements sorted by distance of median
//I do not care about ties.
 
int *sorted_by_distance_of_median(int v[], int n){
 
    int median;
    int *p = (int*)malloc(n*sizeof(int));
    int *v_sorted= (int*)malloc(n*sizeof(int));
    int *dist_to_median = (int*)malloc(n*sizeof(int));
 
 
    for(int i = 0; i < n; i++){
        v_sorted[i] = i;
    }
 
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n-1; j++){
            if(v[v_sorted[j]] > v[v_sorted[j+1]]){
                int aux = v_sorted[j];
                v_sorted[j] = v_sorted[j+1];
                v_sorted[j+1] = aux;
            }
        }
    }
 
    median = v[v_sorted[n/2]];
 
    for(int i = 0; i < n; i++){
        dist_to_median[i] = v[i]-median;
        if(dist_to_median[i] < 0)
            dist_to_median[i] = -dist_to_median[i];
    }
 
    for(int i = 0; i < n; i++)
        p[i] = i;
 
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n-1; j++){
            if(dist_to_median[p[j]] > dist_to_median[p[j+1]]){
                int aux = p[j];
                p[j] = p[j+1];
                p[j+1] = aux;
            }
        }
    }
 
    free(dist_to_median);
    free(v_sorted);
    return p;
}
 
int main(int argc, char *argv[]){
 
    int v[6];
    v[0] = 5;
    v[1] = 3;
    v[2] = 4;
    v[3] = 1;
    v[4] = 2;
    v[5] = 1;
    int n = 6;
 
    int *p = sorted_by_distance_of_median(v,n);
    
 
    for(int i = 0; i < n; i++){
        printf("%d ",p[i]);
    }
    printf("\n");
    
    free(p);
    return 0;
}