Vfrdtyky

import java.util.Scanner;



public class GuessingGame {



private Scanner reader;



public GuessingGame() {

    // use only this scanner, othervise the tests do not work

    this.reader = new Scanner(System.in);

}



public void play(int lowerLimit, int upperLimit) {

    instructions(lowerLimit, upperLimit);

    boolean isAboveAverage;

    int counter = -1;



    while (counter < howManyTimesHalvable(upperLimit - lowerLimit)) {

        isAboveAverage = isGreaterThan(average(lowerLimit, upperLimit));

        if (upperLimit == lowerLimit) {

            break;

        }

        if (isAboveAverage) {

            lowerLimit = average(lowerLimit, upperLimit);

        } else {

            upperLimit = average(lowerLimit, upperLimit);

        }

        counter++;

    }



    System.out.println("your number is " + upperLimit);

}



// implement here the methods isGreaterThan and average

public boolean isGreaterThan(int number) {

    boolean isGreater = false;

    boolean isCorrectAnswerGiven = false;



    while (!isCorrectAnswerGiven) {

        System.out.println("Is your number greater than " + (number) + "? (y/n)");

        String answer = reader.nextLine();



        if (answer.equals("yes") || answer.equals("y")) {

            isGreater = true;

            isCorrectAnswerGiven = true;

        } else if (answer.equals("no") || answer.equals("n")) {

            isCorrectAnswerGiven = true;

        }

    }



    return isGreater;

}



public int average(int upperLimit, int lowerLimit) {

    return (upperLimit + lowerLimit) / 2;

}



public int average2(int firstNumber, int secondNumber) {

    double res = (firstNumber + secondNumber) / 2.0;

    Math.round(res);

    //System.out.println(res);

    return (int) res;

}



public void instructions(int lowerLimit, int upperLimit) {

    int maxQuestions = howManyTimesHalvable(upperLimit - lowerLimit);



    System.out.println("Think of a number between " + lowerLimit + "..." + upperLimit + ".");



    System.out.println("I promise you that I can guess the number you are thinking with " + maxQuestions + " questions.");

    System.out.println("");

    System.out.println("Next I'll present you a series of questions. Answer them honestly.");

    System.out.println("");

}



// a helper method:

public static int howManyTimesHalvable(int number) {

    // we create a base two logarithm  of the given value



    // Below we swap the base number to base two logarithms!

    return (int) (Math.log(number) / Math.log(2)) + 1;

 }

}

I have problems debugging this code. In this class, i'm supposed to implement a simple AI which guesses a number based on your answer on the question "is your number higher then " + a number. My problems are a. the code does never reach the end of the range given (so, with a range from 1 to 10, it never guesses 1 or 10) and b. is does not stop in time. Java often repeats a question multiple times, but the program should say the answer as soon as it could know it.

My fault obviously lies in the play-method (I included the whole class for completeness), I just don't know where. My program functions, so a typo or programming fault is not likely. I must do something wrong in my logic, but I don't know what. Does anybody know where the error lies?

There are some problems with your logic:

• You are calculating howManyTimesHalvable in every iteration. This doesn't make sense considering the incrementation of counter. The last possible value for it is always 1 which can be far lower than current counter.


• You are checking if upper and lower are the same immediately after asking a question without updating those values. Just move it to the end of the loop.


• Last thing is that you need to increment the average by 1 when updating the lowerLimit. If the answer to "Is your number greater than X" is yes, then the new lowerLimit can't be X.

Corrected method:

public void play(int lowerLimit, int upperLimit) {

    instructions(lowerLimit, upperLimit);

    boolean isAboveAverage;

    int counter = howManyTimesHalvable(upperLimit - lowerLimit);

    while (counter > 0) {

        isAboveAverage = isGreaterThan(average(lowerLimit, upperLimit));

        if (isAboveAverage) {

            lowerLimit = average(lowerLimit, upperLimit)+1;

        } else {

            upperLimit = average(lowerLimit, upperLimit);

        }

        if (upperLimit == lowerLimit) {

            break;

        }

        counter--;

    }

    System.out.println("your number is " + upperLimit);

}