Kata

Let's implement Caesar cipher in BF.

Background

The Caesar cipher is a popular encryption algorithm that shifts each alphabet in a string (in this kata, to the right) by a predetermined amount.

For example, A with 5 shifts becomes F, X with 4 shifts becomes B.

Shifting Z causes it to wrap back to A.

  A -> B -> C -> D -> E -> F (5 shifts)
  X -> Y -> Z -> A -> B      (4 shifts)

Non-alphabetical characters are unaffected.

Input

The input string is provided in the format \3INPUTSTRING\0, where:

• First character: the number of shifts as a charcode, from 0 to 127 (inclusive).
• Second to last character: string to be encrypted, terminated by \0 (only spaces and uppercase characters are tested here).

Output

Resultant string generated from the Caesar cipher.

Example

"\1A\0"    -> "B"
"\1Z\0"    -> "A"
"\1ABC\0"  -> "BCD"
"\2A  Z\0" -> "C  B"

Further Reading

• Wikipedia - Caesar cipher

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Have fun 😀