ArrayHunt.java Source code

Introduction

Here is the source code for ArrayHunt.java

Source

/*
 * 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;
        }
    }
}