Given a sorted list of words in an alien language, derive the order of its characters.
The words encode a partial order among characters. Convert each adjacent pair into a directed edge, then topologically sort. The traps are the prefix edge case and spotting contradictions. Here is the full solution with cycle handling.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
The words encode a partial order among characters. Convert each adjacent pair into a directed edge, then topologically sort. The traps are the prefix edge case and spotting contradictions. Here is the full solution with cycle handling.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
