← Maven Clinic Interview Insights
Knew this one from grinding interval problems.
Reframe the problem as finding the maximum number of non-overlapping intervals, then subtract that from the total number of intervals. Use a greedy algorithm: sort intervals by end time and iteratively select the next interval that starts after the last selected end time. The minimum removals equals total intervals minus the maximum non-overlapping intervals.
Pro tip: Mention that this is equivalent to the interval scheduling maximization problem, and that sorting by end time is optimal. Also, clarify edge cases like empty input or intervals with equal start/end times to show thoroughness.
Confirm that intervals are closed (e.g., [1,2] and [2,3] are considered overlapping) and that the goal is to remove the fewest intervals to eliminate all overlaps.
Recognize that minimizing removals is equivalent to maximizing the number of non-overlapping intervals that can be kept.
Sort intervals by their end times. Iterate through them, selecting an interval if its start time is greater than or equal to the end time of the last selected interval.
Count the selected intervals (max non-overlapping set). The minimum removals is total intervals minus this count.
State that sorting takes O(n log n) time and the iteration takes O(n) time, so overall O(n log n) time and O(1) extra space (if sorting in place).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.