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  1. Caesar Cipher
  2. Discussions

Caesar Cipher

  • callumjhays
     + 0 comments

    Java 15 using streams API:

        public static String caesarCipher(String s, int k) {
        return s.chars()
            .map(c -> {
                var isUpperLetter = 'A' <= c && c <= 'Z';
                var isLowerLetter = 'a' <= c && c <= 'z';
                if (isUpperLetter || isLowerLetter) {
                    var wrapStart = isUpperLetter ? 'A' : 'a';
                    var wrapEnd = isUpperLetter ? 'Z' : 'z';
                    var alphabetIdx = c - wrapStart;
                    var alphabetSize = wrapEnd - wrapStart + 1;
                    var newAlphabetIdx = (alphabetIdx + k) % alphabetSize;
                    return wrapStart + newAlphabetIdx;
                } else {
                    // c is not alphabetical. Skip it.
                    return c;
                }
            })
            .collect(
                StringBuilder::new, 
                StringBuilder::appendCodePoint, 
                StringBuilder::append
            )
            .toString();
    }