Implement tail -n for a Very Large File

# Implement tail -n for a Very Large File Design and implement the core of `tail -n`: given a seekable file and a non-negative integer `n`, return the final `n` logical lines without reading the entire file when the requested suffix is small. The file may be many gigabytes. Explain binary-versus-text handling, newline semantics, chunk boundaries, decoding, and complexity. You may first solve for bytes with `\n` as the delimiter, then explain how decoded text is produced safely. ### Constraints & Assumptions - The file is seekable and its size can be queried. - Reads should occur in bounded chunks from the end toward the beginning. - A file may be empty or may end with or without a newline. - `n == 0` returns an empty result. ### Clarifying Questions to Ask - Does a trailing newline create an additional empty logical line? - Which encoding is used, and how should invalid byte sequences be handled? - Must output preserve exact line-ending bytes? - Can the file change while it is being read? ### What a Strong Answer Covers - Backward block reads with correct prepending and stopping conditions - No lost or duplicated bytes at chunk boundaries - Explicit trailing-newline and empty-file behavior - Decoding only after complete byte ranges are assembled - Worst-case complexity and snapshot or mutation assumptions ### Follow-up Questions - What changes for a non-seekable stream? - How would you implement follow mode for an actively growing file? - How would file rotation be detected? - What test cases expose off-by-one newline bugs?