Imagine you're planning a trip using a network of bus routes. Given a set of routes and start/end locations, find the fewest number of buses you must take to reach your destination.

Imagine an empty grid that represents the sea. You are given a sequence of coordinates to add land (islands) to the grid one by one. Determine the number of islands after each addition.

You are given a sorted list of words from an alien language and need to deduce the order of the letters in that language. Determine the alien alphabet order based on the given word sequence.