Took me a while to cut through the SQS flavor text and see what was actually being asked.
First, clarify the problem and constraints, then propose an efficient algorithm using prefix sums and a greedy strategy. Explain that you track prefix sums and insert elements to break zero-sum subarrays, and analyze time and space complexity.
Pro tip: Demonstrate maturity by discussing edge cases (e.g., all zeros, large arrays) and mentioning that the greedy approach is optimal because each insertion can break multiple zero-sum subarrays. Also, relate it to real-world scenarios like message queues to show practical insight.
Restate the problem in your own words and ask clarifying questions about constraints, input size, and expected output.
Recognize that a zero-sum subarray corresponds to two equal prefix sums. Inserting elements can change prefix sums to avoid duplicates.
Use a greedy approach: iterate through the array, maintain a set of seen prefix sums, and when a duplicate is found, insert an element (e.g., 1) to reset the set and increment count.
State that the algorithm runs in O(n) time and O(n) space, and explain why it's optimal.
Walk through a small example to verify correctness and discuss edge cases like empty array or all zeros.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.