Which modification to the min-heap approach is necessary to correctly compute the minimum number of meeting rooms?
hard🎤 Interviewer Follow-up Q15 of Q15
Intervals - Meeting Rooms II (Minimum Conference Rooms)
Suppose meetings can be scheduled with negative start or end times (e.g., representing times before a reference point). Which modification to the min-heap approach is necessary to correctly compute the minimum number of meeting rooms?
AAdjust the comparison in the heap to handle negative end times by using a max-heap instead of min-heap.
BSort intervals by absolute value of start times to handle negative values correctly.
CSort intervals normally by start time and use the min-heap approach as usual; negative times do not affect logic.
DNo modification needed; the existing min-heap approach works regardless of negative times.
Step-by-Step Solution
Step 1: Understand sorting by start time works with negative values.
Sorting by start time orders intervals correctly even if times are negative.
Step 2: Confirm min-heap logic remains valid.
Heap tracks earliest end time; negative values do not affect min-heap property or comparison logic.
Step 3: No need for absolute value sorting or max-heap.
Using absolute values or max-heap breaks the logic of interval ordering and room reuse.
Final Answer:
Option C -> Option C
Quick Check:
Negative times do not change sorting or heap logic [OK]
Quick Trick:Sorting by start time works even with negative times [OK]
Common Mistakes:
MISTAKES
Sorting by absolute values breaks interval order
Switching to max-heap unnecessarily
Assuming negative times require special handling
Trap Explanation:
PITFALL
Negative times might seem to require special handling, but sorting and min-heap logic are unaffected.
Interviewer Note:
CONTEXT
Tests candidate's understanding of algorithm robustness under relaxed constraints.
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