NumberMagicEasy.java

// BEGIN CUT HERE
// PROBLEM STATEMENT
// NOTE: This problem statement contains images that may not display properly if
// viewed outside of the applet.

/*
 * Taro shows a magic trick to Hanako.
 * 
 * 
 * 
 * Taro: Hello Hanako. I'll show you a magic trick. Please imagine a positive
 * integer less than or equal to 16. Hanako: OK. I imagined it. Taro: (Taro
 * shows card 1 to Hanako.) Does this card contain your number? Hanako: Yes.
 * Taro: (Taro shows card 2 to Hanako.) Does this card contain your number?
 * Hanako: No. Taro: (Taro shows card 3 to Hanako.) Does this card contain your
 * number? Hanako: Yes. Taro: (Taro shows card 4 to Hanako.) Does this card
 * contain your number? Hanako: Yes. Taro: Your number is 5!
 * 
 * 
 * 
 * 
 * (Card 1 contains 1, 2, 3, 4, 5, 6, 7 and 8. Card 2 contains 1, 2, 3, 4, 9,
 * 10, 11 and 12. Card 3 contains 1, 2, 5, 6, 9, 10, 13 and 14. Card 4 contains
 * 1, 3, 5, 7, 9, 11, 13 and 15.)
 * 
 * 
 * Your task is to write a program that simulates this magic trick. You are
 * given Hanako's answers in the String answer. The i-th character is 'Y' if she
 * answered "yes" to the i-th question, and 'N' if she answered "no" to the i-th
 * question. Return the integer Hanako imagined.
 * 
 * DEFINITION Class:NumberMagicEasy Method:theNumber Parameters:String
 * Returns:int Method signature:int theNumber(String answer)
 * 
 * 
 * CONSTRAINTS -answer will contain exactly 4 characters. -Each character in
 * answer will be 'Y' or 'N'.
 * 
 * 
 * EXAMPLES
 * 
 * 0) "YNYY"
 * 
 * Returns: 5
 * 
 * The example from the statement.
 * 
 * 1) "YNNN"
 * 
 * Returns: 8
 * 
 * 8 is the only number that exists on the first card and does not exist on any
 * other cards.
 * 
 * 2) "NNNN"
 * 
 * Returns: 16
 * 
 * 
 * 
 * 3) "YYYY"
 * 
 * Returns: 1
 * 
 * 
 * 
 * 4) "NYNY"
 * 
 * Returns: 11
 */
// END CUT HERE
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

public class NumberMagicEasy
{

    public static void main(final String[] args)
    {
        final NumberMagicEasy temp = new NumberMagicEasy();
        final String answer = args[0];
        System.out.println(temp.theNumber(answer));
    }

    public int theNumber(final String answer)
    {

        for (int i = 0; i < answer.length(); i++)
        {
            final Character c = answer.charAt(i);
            final List<Integer> card = cards.get(i);

            if (c.equals('Y'))
            {
                final Set<Integer> newAnswerSet = new HashSet<Integer>();
                for (final int n : card)
                {
                    if (answerSet.contains(n))
                    {
                        newAnswerSet.add(n);
                    }

                }
                // 答えの集合を更新
                answerSet = newAnswerSet;
            }
            else
            // No
            {
                for (final int n : card)
                {
                    answerSet.remove(n);
                }
            }

        }
        if (answerSet.isEmpty())
        {
            return 16;
        }
        final Integer result = (Integer) answerSet.toArray()[0];
        return result;
    }

    public NumberMagicEasy()
    {
        {
            c1.add(1);
            c1.add(2);
            c1.add(3);
            c1.add(4);
            c1.add(5);
            c1.add(6);
            c1.add(7);
            c1.add(8);
        }
        {
            c2.add(1);
            c2.add(2);
            c2.add(3);
            c2.add(4);
            c2.add(9);
            c2.add(10);
            c2.add(11);
            c2.add(12);
        }
        {
            c3.add(1);
            c3.add(2);
            c3.add(5);
            c3.add(6);
            c3.add(9);
            c3.add(10);
            c3.add(13);
            c3.add(14);
        }
        {
            c4.add(1);
            c4.add(3);
            c4.add(5);
            c4.add(7);
            c4.add(9);
            c4.add(11);
            c4.add(13);
            c4.add(15);
        }
        {
            cards.add(c1);
            cards.add(c2);
            cards.add(c3);
            cards.add(c4);
        }

    }

    Set<Integer> answerSet = new HashSet<Integer>();
    List<Integer> c1 = new ArrayList();
    List<Integer> c2 = new ArrayList();
    List<Integer> c3 = new ArrayList();
    List<Integer> c4 = new ArrayList();
    /*
     * (Card 1 contains 1, 2, 3, 4, 5, 6, 7 and 8. Card 2 contains 1, 2, 3, 4,
     * 9, 10, 11 and 12. Card 3 contains 1, 2, 5, 6, 9, 10, 13 and 14. Card 4
     * contains 1, 3, 5, 7, 9, 11, 13 and 15.)
     */
    List<List<Integer>> cards = new ArrayList<List<Integer>>();

    {
        answerSet.add(1);
        answerSet.add(2);
        answerSet.add(3);
        answerSet.add(4);
        answerSet.add(5);
        answerSet.add(6);
        answerSet.add(7);
        answerSet.add(8);
        answerSet.add(9);
        answerSet.add(10);
        answerSet.add(11);
        answerSet.add(12);
        answerSet.add(13);
        answerSet.add(14);
        answerSet.add(15);
    }
}

初参加
書き終えるころにbit演算でやればいいことに気づいた