Thread: Can counting sort sort in descending order?

Of course:

Code:

static void counting_sort ( int *array, int size )
{
  int *counter;
  int i, j, k = size - 1;
  int max = array[0];

  for ( i = 0; i < size; i++ ) {
    if ( array[i] > max )
      max = array[i];
  }

  counter = malloc ( ( max + 1 ) * sizeof *counter );
  if ( counter == NULL )
    return;

  for ( i = 0; i < max; i++ )
    counter[i] = 0;

  for ( i = 0; i < size; i++ )
    counter[array[i]]++;

  for ( i = 0; i < max + 1; i++ ) {
    for ( j = 0; j < counter[i]; j++ )
      array[k--] = i;
  }

  free ( counter );
}

-Prelude

>But how is your version descending?
Instead of copying from 0 to size-1 into array, you do the reverse for a descending sort.

-Prelude