import java.util.ArrayList;
import java.util.Scanner;
 
public class GuessNumber
{
  public static short range;
  public static ArrayList<Integer> collection = new ArrayList<Integer>();
 
  public static void main(String args[])
  {
    // We need a range
    System.out.print("\nI need a range from 0 to 32,767.\n\nPlease choose a number: ");
 
    // Get and populate the range
    Scanner input = new Scanner(System.in);
    range = input.nextShort();
    range = (range == 0) ? 1 : range;
    for (int i=0; i<=range; i++) collection.add(i);
 
    // A few ground rules
    System.out.printf("\nNow pick a number in the range 0 to %s and remember\n", range);
    System.out.println("it. I will then try to guess the number you chose.\n");
    System.out.println("Answer \"yes\" or \"no\" to the questions.\n\n---");
 
    // Keep asking as long as found is false
    boolean found = false;
    while ( ! found)
    {
      // Get the size of the collection
      int size = collection.size();
 
      // As long as there are two or more numbers left
      if (size > 2)
      {
        // The centre index
        int centre = size / 2;
        int theNumber = collection.get(centre);
 
        // Default question
        System.out.printf("\nIs your number less than %s? ", theNumber);
 
        // Evaluate input
        String answer = input.next();
        if (answer.equals("yes") || answer.equals("1")) delete(theNumber, true);
        else if (answer.equals("no") || answer.equals("0")) delete(theNumber, false);
        else { error(answer); found = true; }
 
        // If only one number is left then we are done.
        if (collection.size() == 1) {
          int num = collection.get(0);
          answer(num);
          found = true;
        }
      }
      // Otherwise there are now 2 values in the array.
      else {
        // Get the two values
        int num1 = collection.get(0);
        int num2 = collection.get(1);
 
        // Ask question and get answer
        System.out.print("\nIs your number greater than " + num1 + "? ");
        String answer = input.next().trim().toLowerCase();
 
        // Resolve answer
        if (answer.equals("yes") || answer.equals("1")) {
          answer(num2);
          found = true;
        } else if (answer.equals("no") || answer.equals("0")) {
          answer(num1);
          found = true;
        } else {
          error(answer);
          found = true;
        }
      }
    }
  }
 
  // Deletes numbers less or greater than n
  public static void delete(int n, boolean lt)
  {
    // Create a temporary collection
    ArrayList<Integer> newCollection = new ArrayList<Integer>();
 
    // Add numbers lesser than n
    if (lt)	{ for (int i:collection) if(i<n) newCollection.add(i); }
    // Add numbers greater than n
    else { n=n-1; for (int i:collection) if(i>n) newCollection.add(i); }
    // Replace the collection with the new one
    collection = newCollection;
  }
 
  // The answer
  public static void answer(int num)
  {
    System.out.println("\n---\n\nThen your number is: " + num);
    System.out.println("\nThank you for playing! To play again press the Up arrow");
    System.out.println("on your keyboard and then Enter.\n\nHave a nice day :)");
  }
 
  // An error
  public static void error(String answer)
  {
    System.out.printf("\nI am a machine. I do not understand \"%s\"...\n", answer);
    System.out.println("\nTo play again press the Up arrow on your keyboard and then Enter.");
  }
}