/* This program uses code from "Algorithms in C, Third Edition,"
 *               by Robert Sedgewick, Addison-Wesley, 1998.
 */

#include <stdio.h>

#define MAX_SIZE 10000

/* sort array S in ascending order.
   N is the number of elements in S. */
void selection(int S[], int N)
{ 
  int i, j;
  for (i = 0; i < N; i++)
  { 
    int min = i;
    for (j = i+1; j < N; j++) 
    {
      if (S[j] < S[min])
      {
        min = j;
      }
    }
    int temp = S[min]; 
    S[min] = S[i]; 
    S[i] = temp;
  } 
}


/* usage: selection_sort input_file output_file
 * 
 * reads a set of numbers from the input file, sorts them,
 * and saves them in sorted order to the output file.
 */
int main(int argc, char ** argv)
{
  int numbers[MAX_SIZE];
  int i, next_number, items_read;

  if (argc != 3)
  {
    printf("selection_sort input_file output_file\n");
    return -1;
  }

  char * input_file = argv[1];
  FILE * fp = fopen(input_file, "rb");

  int counter = 0;
  while(1)
  {
    items_read = fscanf(fp, "%d", &next_number);
    if (items_read != 1) 
    {
      break;
    }    

    numbers[counter] = next_number;
    counter++;
    if (counter == MAX_SIZE)
    {
      break;
    }
  }
  fclose(fp);
  
  selection(numbers, counter);

  char * output_file = argv[2];
  fp = fopen(output_file, "wb");
  for (i = 0; i < counter; i++)
  {
    fprintf(fp, "%d\n", numbers[i]);
  }
  fclose(fp);

  printf("sorted %d numbers, the result is stored at file %s\n", 
         counter, output_file);
}