Start by clarifying requirements: supported operations, formula syntax, evaluation strategy, and error handling. Then outline a design using a dependency graph and choose lazy evaluation with memoization for efficiency. Finally, discuss cycle detection via DFS and how to maintain state consistency on errors.
Pro tip: Mention that you would use a topological sort or DFS with a recursion stack for cycle detection, and that you would validate the entire formula before committing any changes to ensure atomicity.
Ask about the exact formula syntax, supported operations (e.g., SUM), evaluation strategy (lazy vs eager), and error handling expectations.
Propose storing cell values and formulas in a map, and maintaining a dependency graph (adjacency list) to track relationships between cells.
Decide between lazy and eager evaluation. Lazy with memoization is often simpler and avoids unnecessary computations, but eager can be more predictable.
Use DFS with a recursion stack to detect cycles when setting a formula or evaluating. Ensure that if a cycle is detected, the state remains unchanged.
On cycle detection, raise an error without modifying existing cell values or dependencies. Validate formulas before applying changes.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.