Caesar Cipher
Julius Caesar protected his confidential information by encrypting it using a cipher. Caesar's cipher shifts each letter by a number of letters. If the shift takes you past the end of the alphabet, just rotate back to the front of the alphabet. In the case of a rotation by 3, w, x, y and z would map to z, a, b and c.
Original alphabet: abcdefghijklmnopqrstuvwxyz
Alphabet rotated +3: defghijklmnopqrstuvwxyzabc
For example, the given cleartext and the alphabet is rotated by . The encrypted string is .
Note: The cipher only encrypts letters; symbols, such as -, remain unencrypted.
Function Description
Complete the caesarCipher function in the editor below. It should return the encrypted string.
caesarCipher has the following parameter(s):
- s: a string in cleartext
- k: an integer, the alphabet rotation factor
Input Format
The first line contains the integer, , the length of the unencrypted string.
The second line contains the unencrypted string, .
The third line contains , the number of letters to rotate the alphabet by.
Constraints
is a valid ASCII string without any spaces.
Output Format
For each test case, print the encoded string.
Sample Input
11
middle-Outz
2
Sample Output
okffng-Qwvb
Explanation
Original alphabet: abcdefghijklmnopqrstuvwxyz
Alphabet rotated +2: cdefghijklmnopqrstuvwxyzab
m -> o
i -> k
d -> f
d -> f
l -> n
e -> g
- -
O -> Q
u -> w
t -> v
z -> b
Solution
const caesarCipher = (string, number) => {
const alphabet = "abcdefghijklmnopqrstuvwxyz".split("");
const input = string.toLowerCase();
let output = "";
for (let i = 0; i < input.length; i++) {
const letter = input[i];
if (alphabet.indexOf(letter) === -1) {
output += letter;
continue;
}
let index = alphabet.indexOf(letter) + number % 26;
if (index > 25) index -= 26;
if (index < 0) index += 26;
output +=
string[i] === string[i].toUpperCase()
? alphabet[index].toUpperCase()
: alphabet[index];
}
return output;
};