Competitive Programming Related · Interview Question

Reference answer

“Competitive programming related” is not a problem specification, so request the exact input/output, constraints, and whether multiple test cases are present. Then narrate a disciplined approach: identify what makes brute force too slow, translate the task into a known structure such as prefix sums, graph traversal, greedy exchange, or dynamic programming, and prove the chosen invariant. Before coding, state time and memory bounds against the largest constraints and decide on input parsing and numeric types. Use examples to test boundary behavior, duplicate values, and disconnected or empty structures when relevant. Do not fill missing details with a favorite template; that produces a polished but potentially wrong answer. A strong interview answer here is the clarification sequence and reasoning process, not an invented solution.

Complexity: For a confirmed linear competitive-programming formulation on n inputs, target O(n) time and O(n) auxiliary space only when the invariant needs stored state.

Then expect these follow-ups

What are the input constraints and required output?
Tests: follow-up reasoning
Which brute-force approach should we improve upon?
Tests: correctness reasoning

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