Build a spreadsheet cell-dependency engine: evaluate formulas and detect circular references.
Sierra's signature build screen: cells hold values or formulas that reference other cells, and editing one has to recompute its dependents without infinite loops. The signal is the dependency graph plus cycle detection. Here is the topological-eval design.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
Sierra's signature build screen: cells hold values or formulas that reference other cells, and editing one has to recompute its dependents without infinite loops. The signal is the dependency graph plus cycle detection. Here is the topological-eval design.
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.
