A Game of Array Hunt

package com.darwinsys;
 
/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002.
 * All rights reserved. Software written by Ian F. Darwin and others.
 * $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun's Java "steaming coffee
 * cup" logo are trademarks of Sun Microsystems. Sun's, and James Gosling's,
 * pioneering role in inventing and promulgating (and standardizing) the Java 
 * language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for
 * inventing predecessor languages C and C++ is also gratefully acknowledged.
 */
 
import java.util.Arrays;
import java.util.Random;
 
/**
 * Array Hunt "game" (pathetic: computer plays itself).
 * 
 * @author Ian Darwin
 * @version $Id: ArrayHunt.java,v 1.3 2004/03/08 00:11:18 ian Exp $
 */
public class ArrayHunt {
    /** the maximum (and actual) number of random ints to allocate */
    protected final static int MAX = 4000;
 
    /** the value to look for */
    protected final static int NEEDLE = 1999;
 
    int[] haystack;
 
    Random r;
 
    public static void main(String[] argv) {
	ArrayHunt h = new ArrayHunt();
	if (argv.length == 0)
	    h.play();
	else {
	    int won = 0;
	    int games = Integer.parseInt(argv[0]);
	    for (int i = 0; i < games; i++)
		if (h.play())
		    ++won;
	    System.out.println("Computer won " + won + " out of " + games + ".");
	}
    }
 
    /** Construct the hunting ground */
    public ArrayHunt() {
	haystack = new int[MAX];
	r = new Random();
    }
 
    /** Play one game. */
    public boolean play() {
	int i;
 
	// Fill the array with random data (hay?)
	for (i = 0; i < MAX; i++) {
	    haystack[i] = (int) (r.nextFloat() * MAX);
	}
 
	// Precondition for binary search is that data be sorted!
	Arrays.sort(haystack);
 
	// Look for needle in haystack
	i = Arrays.binarySearch(haystack, NEEDLE);
 
	if (i >= 0) { // Found it, we win.
	    System.out.println("Value " + NEEDLE + " occurs at haystack[" + i + "]");
	    return true;
	} else { // Not found, we lose.
	    System.out.println("Value " + NEEDLE + " does not occur in haystack; nearest value is " + haystack[-(i + 2)] + " (found at " + -(i + 2) + ")");
	    return false;
	}
    }
}