Gas Station pays off spotting a greedy invariant that turns O(n²) into O(n). Two facts carry the whole solution: total feasibility, and that a failed prefix lets you skip every start within it.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
Gas Station pays off spotting a greedy invariant that turns O(n²) into O(n). Two facts carry the whole solution: total feasibility, and that a failed prefix lets you skip every start within it.
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.
