/* File: binary_search.c
   
   Testing Binary Search
*/

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <time.h>
#include "sorting.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.
*/

index b_search(data key, data A[], index low, index 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 b_search(key, A, mid+1, high) ;
   } else {
      return b_search(key, A, low, mid - 1) ;
   }

}

main(int argc, char *argv[]) {
data *A, key ;
index n, i, r ;
long seed ;
int count, reps ;
   
   if (argc != 4) {
      fprintf(stderr, "Usage: binary_search filename reps rseed \n") ;
      exit(-1) ;
   }

   /* Get number of repetitions */
   r = sscanf(argv[2], "%d", &reps) ;
   if (r != 1) {
      printf("Number of repetitions must be an integer!\n") ;
      exit(-1) ;
   }

   /* Set random seed */ 
   r = sscanf(argv[3], "%ld", &seed) ;
   if (r != 1) {
      printf("Random seed must be an integer!\n") ;
      exit(-1) ;
   }
   srand48(seed) ;

   n = readarray(argv[1], &A) ;

   printf("n = %d\n", n) ;

   count = 0 ;
   for (i = 0 ; i< reps ; i++) {
      key = (data) lrand48() ;
      r = b_search(key, A, 0, n-1) ;

      if (r >= 0) {
	 printf("Found: key = %12d, A[%07d] = %12d\n", key, r, A[r]) ;
	 count++ ;
      }
   }
   printf("Number of hits: %d\n", count) ;
}