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

const int True = 1;
const int False = 0;

void sel_sort( int [ ], int );
void swap( int*, int* );
int sorted( const int [ ], int, int );

main()
{
   int a[ ] = { 5, 4, 3, 2, 1 };
   int i;
   int n = 5;

   sel_sort( a, n );

   for ( i = 0; i < n; i++ )
      printf( "%d\n", a[ i ] );

   return EXIT_SUCCESS;
}

void sel_sort( int a[ ], int n )
{
   int min_ind, i, j;

   for ( i = 0; i < n - 1; i++ ) {
      assert( i >= 0 );
      assert( i < n );
      min_ind = i;
      j = i + 1;
      /* find next smallest */
      do {
         assert( j >= 0 );
         assert( j < n );
         assert( min_ind >= 0 );
         assert( min_ind < n );
         if ( a[ j ] < a[ min_ind ] )
            min_ind = j;
      } while ( ++j < n );
      assert( min_ind >= 0 );
      assert( min_ind < n );
      /* place next smallest at correct slot */
      swap( &a[ i ], &a[ min_ind ] );
      assert( sorted( a, i, n ) );
   }
}

void swap( int *cell1, int *cell2 )
{
   int temp;

   temp = *cell1;
   *cell1 = *cell2;
   *cell2 = temp;
}

/* Returns True if

      a[ 0 ],a[ 1 ],...,a[ i ]

   are sorted and

      a[ j ] >= a[ i ]

   for all j, i < j < n. Returns False
   otherwise.
*/

int sorted( const int a[ ], int i, int n )
{
   int j;

   for ( j = 0; j <= i; j++ )
      if ( a[ j ] > a[ j + 1 ] )
         return False;

   for ( j = i + 1; j < n; j++ )
      if ( a[ j ] < a[ i ] )
         return False;

   return True;
}