/* SortAndSearch.java
 *  A demonstration of the bubble sort algorithm
 *  and the binary search algorithm.
 *   Illustrates distinction between declared array size and 
 *    logical size (# elements actually stored in it)
 *
 *  @author  Dr. Henry H. Leitner
 *  @version Last Modified November 23, 2008
 */
import java.util.*;

class SortAndSearch
{
  private static final int MAX_ARRAY_SIZE = 100;
  private static final int ACTUAL_SIZE = 10;

  static void printArray ( int [] a, int size)
  {
     for (int i = 0; i < size; i++ )
     {
        System.out.println("Element [" + i + "] = " + a[i] );
     }
  }

    /**
     *  This method accepts an array and a size (n), and then sorts n 
     *  elements beginning at position 0 using a bubblesort algorithm.
     *
     *  @param    a     the array to be sorted
     *  @param   size   the number of elements to sort
     */
   static void bubblesort (int [] a,        // an array of numbers 
                           int n )          // # of elements in array a
   {
     

     for (int i = 1; i < n; i++)           // sort a[0..size-1] 
     {                                     // into non-descending   
       for (int j = n-1; j >= i; j--)      // order by exchange method.  This      
       {                                   // will leave a[0]; then a[1]; then     
                    // a[2]; ... then a[n-1]; with their correct values.    
                    // In other words, the j-FOR-loop always gets a[i-1]    
                    // set to the right value by "bubbling" the smallest    
                    // value in a[i-1], a[i], a[i+1], ..., down to position 
                    // a[i-1] 
    
          if (a [j - 1] > a[j])           // If true, then the j-1'st and the 
          {                               // j'th elements of a are out of    
              int temp     = a[j - 1];    // order. They will be swapped!     
              a[j - 1] = a[j];
              a[j]     = temp;
          }
      }
    }
  }

  /** performs a binary search for item in array a[left..right] 
   *  Returns array index where item was found, or -1 if not found
   */
  static int binary (int a[], int item, int left, int right)
  {
      if (left > right) return -1;
      else 
      {
         int middle = (left + right) / 2;  // integer division 
         if (item == a[middle]) return middle;
         else if (item > a[middle]) 
               return binary(a, item, middle+1, right);
         else  return binary(a, item, left, middle-1);
      }
  }


  public static void main (String[] args)
  {
    int  itemLoc;
    int[] list = new int [MAX_ARRAY_SIZE]; // elements init'd to 0
    Scanner keyboard = new Scanner (System.in);
    
    System.out.print("Do you want randomly assigned values? ");
    String response = keyboard.nextLine();
    char yOrn = response.charAt(0);
    for (int i = 0; i < ACTUAL_SIZE; i++ ) 
    {
       System.out.print ("Input an array element #" + i + ":  ");
       if (yOrn == 'y' || yOrn == 'Y')
         {
           list[i] = (int) (Math.random() * 100);
           System.out.println( list[i] );
         }
       else list[i] = keyboard.nextInt();
    }
   
    bubblesort (list, ACTUAL_SIZE); // sort the list into ascending order 
    System.out.println 
            ("\nHere is the array sorted into non-descending order:");
    printArray (list, ACTUAL_SIZE); 
    System.out.println( Arrays.toString( list ) );
    do
    {
        System.out.print ("\nNow which value shall I search for? ");
        int i = keyboard.nextInt();
	    response = keyboard.nextLine();   // WHY???
        itemLoc = binary (list, i, 0, ACTUAL_SIZE - 1);
        if (itemLoc >= 0)
            System.out.println ("Found " + i + " at location " + itemLoc);
        else
            System.out.println 
                    ("Could NOT find the value " + i + " in the array!");
            
        System.out.print ("Want to search for another value? [yes or no] ");
        response = keyboard.nextLine();
    } while (response.charAt(0) != 'N' && response.charAt(0) != 'n');
  }
}