Created
July 23, 2012 13:53
-
-
Save robbielynch/3163739 to your computer and use it in GitHub Desktop.
Caesar Cipher - I made this caesar cipher decrypter to solve hackerrank.com puzzles.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| import java.util.Scanner; | |
| public class CaesarCipher { | |
| private static char []letters = | |
| { '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' | |
| ,'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' | |
| ,'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' | |
| }; | |
| public static void main(String args[]){ | |
| Scanner in = new Scanner(System.in); | |
| System.out.println("Encrypted Word"); | |
| String encryptedAnswer = in.nextLine(); | |
| System.out.println("Decrypted Word"); | |
| String decryptedAnswer = in.nextLine(); | |
| System.out.println("String to decode:"); | |
| String encryptedString = in.nextLine(); | |
| String decryptedString = ""; | |
| int diff = 0; | |
| //calculate difference between letters | |
| encryptedAnswer = encryptedAnswer.toLowerCase(); | |
| decryptedAnswer = decryptedAnswer.toLowerCase(); | |
| char enfirst = encryptedAnswer.charAt(0); | |
| char defirst = decryptedAnswer.charAt(0); | |
| int e = (int) enfirst; | |
| int d = (int) defirst; | |
| //get difference between the 2 letters | |
| diff = d - e; | |
| //System.out.println("diff = " + diff); | |
| System.out.println(encryptedString); | |
| int startMiddleLetters = 26; | |
| //decrypt string | |
| for(int i = 0; i < encryptedString.length();i++){ | |
| //get current char | |
| char curChar = encryptedString.charAt(i); | |
| if(curChar != ' ' && curChar != ',' && curChar != '-'){ | |
| //Get number of current char | |
| int curCharInt = (int)curChar; | |
| //Calculate position of the current char in the middle section of the letters array | |
| int posOfCurCharInLettersArray = (curCharInt - 97) + startMiddleLetters; //97 is 'a' in ascii | |
| //get position of decrypted char | |
| int posOfNewCharInLettersArray = posOfCurCharInLettersArray + diff; | |
| //get decrypted char | |
| char newChar = letters[posOfNewCharInLettersArray]; | |
| //build output string | |
| decryptedString += newChar; | |
| }else{ | |
| //build output string | |
| decryptedString += curChar; | |
| } | |
| } | |
| //output decrypted string | |
| System.out.println(decryptedString); | |
| } | |
| } |
great work on this!
I made a few modifications in my fork including the use of command line arguments, a StringBuffer, and modulus arithmetic to simplify the letters char array.
:: devon
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
To become a beta user of hackerrank.com, you have to solve 100 puzzles... all of which use the Caesar Cipher.
To make things quicker, I created this...
I struggled for a while getting stringIndexOutOfBounds error because there was my ASCII calculations were off, then realised if I had a char array with 3 sets of letters from(a -> z), then by referencing the middle set of letters, it would be very easy to add and subtract the index without getting errors.