Use a stack to track the currently executing function and maintain a running total of exclusive time. When a function starts, push its ID and start time; when it ends, compute its exclusive time by subtracting nested calls, then add that time to the parent's exclusive time if a parent exists.
Pro tip: Clarify the log format and edge cases upfront—like whether timestamps are inclusive/exclusive and if nested calls can span multiple logs—to avoid off-by-one errors and show attention to detail.
Confirm the structure of each log entry (e.g., 'function_id:start:timestamp' or 'function_id:end:timestamp') and whether timestamps are integers representing time units. Ask about edge cases like multiple functions with the same ID or non-nested sequential calls.
Use a stack to store pairs of (function_id, start_time) for currently executing functions. Use a hash map or array to accumulate exclusive time per function ID.
For each log: if it's a start, push the function ID and timestamp onto the stack. If it's an end, pop the top, compute exclusive time as (end_time - start_time + 1) minus any time spent in nested calls (tracked via a variable or by adjusting parent's start time), and add to the function's total.
When a function ends, if the stack is not empty, the parent's exclusive time should be reduced by the child's total execution time (including nested calls). Alternatively, update the parent's start time to the child's end time + 1 to account for the child's duration.
After processing all logs, return the exclusive times for each function. Walk through a simple example (e.g., single function, nested functions) to verify correctness and discuss time/space complexity.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.