fork download
copy 
  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10.  
  11.     private static final class CypherText {
  12.         private final int key;
  13.         private final String text;
  14.  
  15.         public CypherText(int key, String text) {
  16.             super();
  17.             this.key = key;
  18.             this.text = text;
  19.         }
  20.  
  21.         public int getKey() {
  22.             return key;
  23.         }
  24.  
  25.         public String getText() {
  26.             return text;
  27.         }
  28.  
  29.     }
  30.  
  31.     public static CypherText getEncoded() {
  32.         try (BufferedReader reader = new BufferedReader(new InputStreamReader(System.in))){
  33.             int k = Integer.parseInt(reader.readLine());
  34.             String word = reader.readLine();
  35.             return new CypherText(k, word);
  36.         } catch (IOException e) {
  37.             e.printStackTrace();
  38.             return new CypherText(0, "");
  39.         }
  40.     }
  41.  
  42.     public static final String decode(final int key, final String encoded) {
  43.         final int len = encoded.length();
  44.         char[] decoded = new char[len];
  45.         for (int i = 0; i < len; i++) {
  46.             decoded[i] = decodeChar(encoded.charAt(i), i + 1, key);
  47.         }
  48.         return new String(decoded);
  49.     }
  50.  
  51.     private static char decodeChar(final char encoded, final int position, final int key) {
  52.         // modulo 26 eliminates multiple wrap-arounds.
  53.         int rotate = (3 * position + key) % 26;
  54.         // apply the rotation shift to the input
  55.         int decval = (encoded - 'A') + 26 - rotate;
  56.         // use another % 26 to keep the letters in range.
  57.         return (char)('A' + (decval % 26));
  58.     }
  59.  
  60.     public static void main(String[] args) {
  61.         CypherText input = getEncoded();
  62.         String decoded = decode(input.getKey(), input.getText());
  63.         System.out.println("Decoded: " + decoded);
  64.     }
  65.  
  66.  
  67. }
Success #stdin #stdout 0.06s 380160KB
comments (?)
stdin
copy 
5
JTUSUKG
stdout
copy 
Decoded: BIGBANG
https://ideone.com/oQKZFe
language:
Java (12.0.1)
created:
9 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!