Implement Tail and Find Monster Cost

This entry contains two coding tasks from the same interview category. ### Task A: Implement a file tail operation Implement a function `tail(filePath, n)` that returns the last `n` lines of a text file in their original order. Requirements: - The input is a real file path, not an in-memory string. You should be comfortable creating a small text file as a test case and reading it back. - If the file has fewer than `n` lines, return all lines. - If `n == 0`, return an empty result. - A trailing newline at the end of the file should not create an extra empty line. - Discuss or implement an approach that does not load the entire file into memory when the file is very large. ### Task B: Find minimum monster cost in a grid You are given a 2D grid representing a dungeon: - `S` is the start cell. - `E` is the exit cell. - `.` is an empty cell with cost `0`. - `M` is a monster cell with cost `1` to enter. - `#` is a wall that cannot be entered. From any cell, you may move up, down, left, or right. Return the minimum total monster cost required to travel from `S` to `E`. If the exit is unreachable, return `-1`. Follow-ups: - Return one path that achieves the minimum cost. - Extend the grid so each monster cell has an arbitrary non-negative integer cost instead of cost `1`.