The skip-not-fail part is what tripped me up at first.
Clarify the requirements and constraints first, then propose a simple data structure like a queue for subtraction requests and a running balance variable. Process additions immediately, and for subtractions, iterate through the queue in order, executing only those that don't exceed the current balance. Finally, return the final balance and the list of executed transactions.
Pro tip: Discuss how your solution would scale if the number of transactions is huge or if subtractions need to be processed in real-time, showing awareness of system design trade-offs.
Ask about input format, whether additions and subtractions are interleaved, and if the order of subtraction requests is strictly FIFO. Confirm expected output format.
Use a queue to store pending subtraction requests in order, and a variable to track the current balance. Consider if additions should be processed immediately or also queued.
Process operations sequentially: for additions, increase balance; for subtractions, enqueue the request. After all operations, or interleaved, process the queue in order, skipping requests that exceed the current balance.
Consider negative amounts, zero balance, large numbers, and empty input. Ensure the algorithm correctly skips only the requests that would overdraw, not subsequent ones.
State time and space complexity. Typically O(n) time and O(n) space for n operations, as each subtraction is processed at most once.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.