/* File: bsearch1.cpp

   A binary search function for a sorted array 
   that we wrote in class.

*/

#include <iostream>
#include <assert.h>
using namespace std ;


// Use binary search to look for stuff in array A[start], .., A[end]
// inclusive. Returns the index i such that A[i] == stuff or
// returns -1 if not found.
//

int bsearch(int A[], int start, int end, int stuff) {

   int middle ;

   while (start <= end) {

      // assert(start <= end) ;

      middle = ( start + end ) / 2 ;

      assert (start <= middle && middle <= end) ;
      
      if ( A[middle] == stuff) {

         return middle ;

      } else if ( A[middle] < stuff ) {

         start = middle + 1 ;

      } else {

         end = middle - 1 ;

      }

   }  // end of while ( ...  )

   return -1 ;

}


int main() {

   int A[15] = { 2, 5, 6, 9, 10, 12, 14, 17, 21, 32, 39, 41, 44, 45, 60 } ;

   int result ;

   result = bsearch(A, 0, 14, 41) ;
   if (result == -1) {
      cout << "41 is not in array A[].\n" ;
   } else {
      cout << "41 is in A[" << result << "]\n" ;
   }

   result = bsearch(A, 0, 14, 23) ;
   if (result == -1) {
      cout << "23 is not in array A[].\n" ;
   } else {
      cout << "23 is in A[" << result << "]\n" ;
   }

   cout << "\n\n" ;

   int plusOne ;

   for (int i=0 ; i < 15 ; i++) {

      result = bsearch(A, 0, 14, A[i]) ;
      if (result == -1) {
	 cout << A[i] << " is not in array A[].\n" ;
      } else {
	 cout << A[i] << " is in A[" << result << "]\n" ;
      }

      plusOne = A[i] + 1 ;

      result = bsearch(A, 0, 14, plusOne) ;
      if (result == -1) {
	 cout << plusOne << " is not in array A[].\n" ;
      } else {
	 cout << plusOne << " is in A[" << result << "]\n" ;
      }

   }

   return 0 ;

}