ECOO Split Code Decryption Solution

Sol1.java

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;


public class Sol1 {

  
	
	
	public static void main (String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new FileReader("in1.txt"));
		BufferedWriter bw = new BufferedWriter(new FileWriter("out1.txt"));
		char[] a1 = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P'};
		char[] a2 = {'Q','R','S','T','U','V','W','X','Y','Z','K','L','M','N','O','P'};
		
		for (int i = 0; i < 1; i++) {
			String encrypt = br.readLine();
			String dealpha = "";
			for (int x = 0; x < encrypt.length(); x++) {
				for (int n = 0; n < a1.length; n++) {
					if (encrypt.charAt(x) == a1[n] || encrypt.charAt(x) == a2[n]) {
						dealpha += Integer.toHexString(n);
						break;
					}
				}
			}
			for (int x = dealpha.length() - 1; x > 0; x--){
				int curr = Integer.parseInt(dealpha.charAt(x) + "", 16);
				int last = Integer.parseInt(dealpha.charAt(x - 1) + "", 16);
				if (curr < last) {
					curr = Integer.parseInt("1" + dealpha.charAt(x), 16);
				}
				
				char[] temp = dealpha.toCharArray();
				temp[x] = Integer.toHexString(curr - last).toCharArray()[0];
				dealpha = "";
				for (char c : temp) {
					dealpha += c;
				}
			}
			//Silly hack to get to ACSII :/
			String out = "";
			for (int x = 0; x < dealpha.length(); x+=2) {
				int temp = Integer.parseInt(Character.toString(dealpha.charAt(x)) + Character.toString(dealpha.charAt(x + 1)), 16);
				out += (char) temp;
			}
			System.out.println(out);
		}
	}
}