Replace Every Nth Consonant

Problem Overview

• Transform a message by replacing every nth consonant with the next consonant, preserving case and wrapping z/Z to b/B.
• Input: string message and integer n; Output: the modified string; non-consonants remain unchanged; time complexity should be no worse than O(message.length^2).
• Consonants use the standard English set (b, c, d, f, ..., z), counted across the string.
• Asked in Meta coding interviews, this interview question focuses on text processing; a practical string manipulation problem.