/* File: sort.c
   Sort a list of numbers.
*/

#include <stdio.h>
#include "genlib.h"
#include "simpio.h"

#define SENTINEL -1
#define MAX_ITEMS 100

int ReadArray(int A[], int max_size) ;
void SelectionSort(int A[], int size) ;
int FindSmallest(int A[], int start, int stop) ;

main() {
   int A[MAX_ITEMS], items, i ;

   printf("Enter items, one per line.\n") ;
   printf("End with sentinel: %d\n", SENTINEL) ;
   
   items = ReadArray(A, MAX_ITEMS) ;

   if (items == -1) {
     printf("Too many items!!!\n") ;
   } else {
      SelectionSort(A, items) ;
      
      printf("\nSorted list:\n") ;
      for(i = 0 ; i < items ; i++) {
	 printf("A[%d] = %d\n", i, A[i]) ;
      }
   }
}


/* Use Selection Sort to sort the array 
*/
void SelectionSort(int A[], int size) {
   int unsorted, smallest_index, temp ;

   for(unsorted=0; unsorted < size-1; unsorted++){

      smallest_index 
	 = FindSmallest(A,unsorted,size-1);

      /* swap values */
      temp = A[smallest_index] ;
      A[smallest_index] = A[unsorted] ;
      A[unsorted] = temp ;
   }
}

/* Find smallest value in array A from start
   to stop.
*/
int FindSmallest(int A[], int start, int stop) {
   int smallest_value, smallest_index, i ;

   smallest_index = start ;
   smallest_value = A[start] ;

   for (i = start+1 ; i <= stop ; i++){
      if (A[i] < smallest_value) {
	 smallest_index = i ;
	 smallest_value = A[i] ;
      }
   }
   return(smallest_index) ;
}


/* Read integers into array.
   Make sure that array size is not exceeded.
   If so, return -1, otherwise return # of items.
*/
int ReadArray(int A[], int max_size) {
  int i, value ;

  i = 0 ;
  while (TRUE) {
     value = GetInteger() ;
     if (value == SENTINEL) break ;
     if (i == max_size) return(-1) ;
     A[i] = value ;
     i++ ;
  }
  return(i) ;
}