// File: bsearch.C
// Testing Binary Search

#include <iostream.h>
#include <iomanip.h>
#include <fstream.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include "array.h"


// Recursively search for item with value equal to key
//   in sorted array A.  Return the index of the item,
//   or -1 if none found.

int bsearch(DATA key, Array A, int low, int high) {
   int mid ;

   // No such item?
   if (low > high) return -1 ;

   mid = (low + high) / 2 ;

   // check middle
   if (A[mid] == key) {
      return mid ;
   } else if (A[mid] < key) {
      return bsearch(key, A, mid+1, high) ;
   } else {
      return bsearch(key, A, low, mid - 1) ;
   }

}

main(int argc, char *argv[]) {

DATA key ;
int n, i, r ;
long seed ;
int count, reps ;
ifstream ifile ;
struct stat sbuf ;


   if (argc != 4) {
      cerr << "Usage: bsearch reps seed fname" << endl ;
      exit(1) ;
   }

   reps = atoi(argv[1]) ;
   seed = atoi(argv[2]) ;

   if (reps <= 0 || seed <= 0) {
      cerr << "Bad size or seed" << endl ;
      exit(1) ;
   }

   // get file size
   //
   r = stat(argv[3], &sbuf) ;
   if (r != 0) {
      cerr << "Cannot get file size" << endl ;
      exit(1) ;
   }

   // n = Number of data items in the file
   //
   n = sbuf.st_size / sizeof(DATA) ;

   cout << "reps = " << reps << " seed = " << seed << endl ;
   cout << "number of items = " << n << endl ;

   ifile.open(argv[3]) ;

   if (ifile == NULL) {
      cerr << "Could not open file " << argv[3] << endl ;
      exit(1) ;
   }

   Array A(n, seed) ;

   ifile.read((char *) A.arr, n * sizeof(DATA) ) ;

   count = 0 ;
   for (i = 0 ; i< reps ; i++) {
      key = (DATA) drand48() ;
      r = bsearch(key, A, 0, A.length()-1) ;

      if (r >= 0) {
         cout << "Found: key = " << key
              << " A[" << r << "] = " << A[r] << endl ;
         count++ ;
      }
   }
   cout << "Number of hits: " << count << endl ;
}