Ordenação por contagem

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

#define MAX 225

void ord_contagem(int *arr,int size)
{
    int retorno[size];
    int count[MAX + 1],i;
    memset(count,0,sizeof(count));

    for(i=0 ; arr[i] ; i++)
        ++count[arr[i]];

    for(i = 1 ; i <= MAX ; i++)
        count[i] += count[i - 1];

    for(i = 0; arr[i] ;i++)
    {
        retorno[ count[arr[i] ] - 1] = arr[i];
        --count[arr[i]];
    }
    for( i = 0 ; arr[i] ; i++)
        arr[i] = retorno[i];
}

int main(void)
{
  int n,a;
  scanf("%d",&n);
  int *vector = (int *)calloc(n,sizeof(int));
  for(a = 0;a < n;a++)
        scanf("%d",&vector[a]);
    ord_contagem(vector,n);
  for(a = 0;a < n-1;a++)
        printf("%d ",vector[a]);
  printf("%d\n",vector[n-1]);
    free(vector);
    return 0;
}