import java.util.Random;
import java.util.Scanner;

public class Nim
{
  public static int total;
  public static Random generator = new Random();
  
  public static void main(String args[])
  {
    // Yada yada yada...
    System.out.println("This is the game of matches. As long as there are mathes left we alternate");
    System.out.println("between taking 1, 2 or 3 matches from the table. The one who takes the last");
    System.out.println("match looses. First, however, we need to know how many matches we will play with.\n");
    System.out.print("Please enter a number from 25 to 100: ");
    
    // Get answer
    Scanner input = new Scanner(System.in);
    int num = input.nextInt();
    total = (num<25||num>100) ? 25 : num;
    
    // And boom goes the dynamite...
    System.out.println("\nOkay. You may start.\n");
    do {
      System.out.print("Your turn: ");
      int response = input.nextInt();
      if (response < 1 || response > 3) System.out.print("Not valid. You may only pick 1, 2 or 3 matches!\n");
      else {
        total -= response;
        System.out.println("\nMatches left: " + total); }
      myTurn();
    } while (total > 1);
    if (total == 1) System.out.println("Oh oh, you have to take the last match!. You loose, muhahaha.");
    else System.out.println("PC lost...");
  }
  
  public static void myTurn()
  {
    int take;
    
    // Nim algorithm goes here...
    // ...
    
    // No algorithm...
    take = generator.nextInt(3) + 1;
    
    // Subtract taken matches
    total -= take;
    
    // Report back
    System.out.println("PC's turn: " + take + "\n");
    System.out.println("Total matches: " + total);
  }
  
}

import java.util.Random;
import java.util.Scanner;

public class Matches
{
  public static int total;
  public static Random generator = new Random();
  
  public static void main(String args[])
  {
    // Yada yada yada...
      System.out.println("This is the game of matches. As long as there are mathes left we alternate");
      System.out.println("between taking 1, 2 or 3 matches from the table. The one who takes the last");
      System.out.println("match looses. First, however, we need to know how many matches we will play with.\n");
      System.out.print("Please enter a number from 25 to 100: ");
      
    // Get answer
      Scanner input = new Scanner(System.in);
      int num = input.nextInt();
      total = (num<25||num>100) ? 25 : num;
      
      // And boom goes the dynamite...
      System.out.println("\nOkay. You may start.\n");
      do {
        System.out.print("Your turn: ");
        int response = input.nextInt();
        if (response < 1 || response > 3) System.out.print("Not valid. You may only pick 1, 2 or 3 matches!\n");
        else {
          total -= response;
          System.out.println("\nMatches left: " + total); }
        myTurn();
      } while (total > 1);
      if (total == 1) System.out.println("Oh oh, you have to take the last match!. You loose, muhahaha.");
      else System.out.println("PC lost...");
  }
  
  public static void myTurn()
  {
    int take;
    
    // Nim algorithm goes here...
    // ...
    
    // No algorithm...
    take = generator.nextInt(3) + 1;
    
    // Subtract taken matches
    total -= take;
    
    // Report back
    System.out.println("PC's turn: " + take + "\n");
    System.out.println("Total matches: " + total);
  }
  
}

nim

Nim (play against PC, without winning algorithm)

Java