Write a RandomCipher function that builds a dictionary where each of the 26 lett

Question

Write a RandomCipher function that builds a dictionary where each of the 26 letters of the alphabet is randomly matched to another (all lowercase). Each of the matching letters should be unique (in other words, your function creates a bijective mapping). Example:

{ 'a':'g', 'b':'i', 'c':'b', 'd':'d', 'e':'y', 'f':'q', 'g':'a', 'h':'p', 'i':'i', 'j':'c', 'k':'y', 'l':'z', 'm':'w',

   'n':'c', 'o':'v', 'p':'z', 'q':'s', 'r':'h', 's':'x', 't':'e', 'u':'v', 'v':'p', 'w':'s', 'x':'j', 'y':'f', 'z':'w' }

Write an Encode function that takes a plain text string as input and returns a new string encrypted using your cypher in part (a). Make sure to replace all letters once only; leave punctuation and other non-alphabetical characters as is. Example: if using the above mapping, the text "hello, world!" would be encoded as "pyzzv, svazd!"

Write a Decode function that takes an encrypted text string as input and returns a new string decrypted using your cypher in part (a). Create any intermediate data structure as required to make your code efficient. Example: "pyzzv, svazd!" should be decoded as "hello, world!" (Encoding followed by decoding should always produce the same string.)

Explanation / Answer

package Mar15th;

import java.util.HashMap;

/*

* Here I am using 2 maps for mapping the letter with other random letter and similarly another map for decode purpose to store reversely

*  

*

*

*/

public class RandomCipher {

static HashMap<String,String>encodeMap = new HashMap<String,String>();

static HashMap<String,String>decodeMap = new HashMap<String,String>();

public static void main(String[] args) {

encodeMap.put("a", "y");

decodeMap.put("y", "a");

encodeMap.put("b", "g");

decodeMap.put("g", "b");

encodeMap.put("c", "f");

decodeMap.put("f", "c");

encodeMap.put("d", "w");

decodeMap.put("w", "d");

encodeMap.put("e", "h");

decodeMap.put("h", "e");

encodeMap.put("f", "x");

decodeMap.put("x", "f");

encodeMap.put("g", "e");

decodeMap.put("e", "g");

encodeMap.put("h", "v");

decodeMap.put("v", "h");

encodeMap.put("i", "c");

decodeMap.put("c", "i");

encodeMap.put("j", "u");

decodeMap.put("u", "j");

encodeMap.put("k", "t");

decodeMap.put("t", "k");

encodeMap.put("l", "d");

decodeMap.put("d", "l");

encodeMap.put("m", "s");

decodeMap.put("s", "m");

encodeMap.put("n", "r");

decodeMap.put("r", "n");

encodeMap.put("o", "b");

decodeMap.put("b", "o");

encodeMap.put("p", "z");

decodeMap.put("z", "p");

encodeMap.put("q", "l");

decodeMap.put("l", "q");

encodeMap.put("r", "m");

decodeMap.put("m", "r");

encodeMap.put("s", "a");

decodeMap.put("a", "s");

encodeMap.put("t", "k");

decodeMap.put("k", "t");

encodeMap.put("u", "o");

decodeMap.put("o", "u");

encodeMap.put("v", "n");

decodeMap.put("n", "v");

encodeMap.put("w", "j");

decodeMap.put("j", "w");

encodeMap.put("x", "p");

decodeMap.put("p", "x");

encodeMap.put("y", "q");

decodeMap.put("q", "y");

encodeMap.put("z", "i");

decodeMap.put("i", "z");

String input = "Hello World..";

String encodedString = encode(input);

System.out.println("Encoded : "+encodedString);

String decoded = decode(encodedString);

System.out.println("Decoded : "+decoded);

}

private static String encode(String aInput) {

aInput = aInput.toLowerCase();

String res="";

for(int i=0;i<aInput.length();i++){

if(Character.isAlphabetic(aInput.charAt(i))){ // If it character than only we should encode so I am checking with help of Character class method isAlphabetic()

res+=encodeMap.get(aInput.charAt(i)+"");

}

else{

res+=aInput.charAt(i);

}

}

return res;

}

private static String decode(String aInput) {

aInput = aInput.toLowerCase();

String res="";

for(int i=0;i<aInput.length();i++){

if(Character.isAlphabetic(aInput.charAt(i))){

res+=decodeMap.get(aInput.charAt(i)+"");

}

else{

res+=aInput.charAt(i);

}

}

return res;

}

}

Note : add comment if your require it in any other language , here I did't find any specific language so i am taking Java language

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