nimgame

js

import java.util.Scanner;
/**Implements a game of nim, person vs. computer.
 * The game starts with a number of elements chosen
 * by the person.  The computer takes 1 or 2 elements.
 * Then the person takes 1 or 2 elements.  The game
 * continues until there are no elements left.  The
 * play who takes the last turn wins.
 * @author Jam Jenkins
 */
public class Nim
{

    /**gets the computer's move, 1 or 2.  Currently
     * this method gets a random number.  Your job
     * is to make the computer choose such that it
     * wins every time it is possible.  First, solve
     * with recursion.  After successfully completing
     * this, run the program a few times to see if you
     * can recognize the pattern the computer is taking.
     * Then see if you can get the computer to choose
     * its move without looping or recursion.
     * @param left
     * @return
     */
    public int getComputerMove(int left)
    {
        return (int)(Math.random()*2)+1;
    }

    /**
     * plays the game of nim, computer versus person
     */
    public void play()
    {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter number of elements to start.");
        int left = sc.nextInt();
        while(left>0)
        {
            int computer=getComputerMove(left);
            System.out.println("Computer takes "+computer);
            left-=computer;
            System.out.println("Now there are "+left+" left.");
            if(left<=0)
            {
                System.out.println("Computer wins!");
                return;
            }
            System.out.println("What's your move? (1 or 2)");
            int person=sc.nextInt();
            while(person!=1 && person!=2)
            {
                System.out.println(person+" not allowed, choose 1 or 2.");
                person=sc.nextInt();
            }
            left-=person;
            System.out.println("Now there are "+left+" left.");
            if(left<=0)
            {
                System.out.println("You win!");
                return;
            }
        }
    }

    public static void main(String[] args)
    {
        Nim nim=new Nim();
        nim.play();
    }
}