The Hardest Problem Ever

From Progteam

The Hardest Problem Ever
Problem Number 1298

Sorter:	Uncategorized
Source:	South Central USA 2002
Link:	http://acm.pku.edu.cn/JudgeOnline/problem?id=1298

The Hardest Problem Ever is problem number 1298 on the Peking University ACM site.

Contents 1 Problem Information 2 Solver Information 3 General Strategy 4 Solution 5 Additional Remarks

Problem Information

Problem Name: The Hardest Problem Ever
Problem Number on PKU: 1298
Synopsis: Simulating Caesar Cipher Scheme.

Solver Information

Solver: Eric Hong
Date: November 02, 2007

General Strategy

1. Using Scanner, take the input.
   
2. Decrypt the message using Caesar Cipher Scheme.
   

Solution

import java.util.*;

public class Main 
{
    public static Scanner in;

    public static void main(String[] args) 
    {
        in = new Scanner(System.in);

        doStuff();
    }

    public static void doStuff() 
    {
        String message = in.nextLine();

        while (!message.equals("ENDOFINPUT"))
        {
            while (! ((message.equals("START")) || (message.equals("END"))))
            {
                solve(message);
                message = in.nextLine();
            }
            message = in.nextLine();
        }
    }

    public static void solve(String message) 
    {
        Caesar cipher = new Caesar();
        String newMessage = cipher.decrypt(message);
        System.out.println(newMessage);
    }
}

class Caesar
{
    public static final int ALPHASIZE = 26;
    public static final char[] alpha = {'A','B','C','D','E','F','G','H', 'I',
        'J','K','L','M', 'N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
    
    protected char[] encrypt = new char[ALPHASIZE];
    protected char[] decrypt = new char[ALPHASIZE];

    public Caesar() 
    {
        for (int i=0; i<ALPHASIZE; i++) 
            encrypt[i] = alpha[(i + 5) % ALPHASIZE];
        for (int i=0; i<ALPHASIZE; i++) 
            decrypt[encrypt[i] - 'A'] = alpha[i];
    }

    public String decrypt(String secret)
    {
        char[] mess = secret.toCharArray();
        for (int i=0; i<mess.length; i++)
            if (Character.isUpperCase(mess[i]))
                mess[i] = decrypt[mess[i] - 'A'];
        return new String(mess);
    }
}

Additional Remarks

Memory: 2444K Time: 312MS