Intervals - Meeting Rooms II (Minimum Conference Rooms)
Given the following intervals: [[0, 30], [5, 10], [15, 20]], what is the output of the optimal min-heap based Meeting Rooms II solution?
Given the following intervals: [[0, 30], [5, 10], [15, 20]], what is the output of the optimal min-heap based Meeting Rooms II solution?
easy🧾 Code Trace Q3 of Q15
Step-by-Step Solution
Solution:
Step 1: Sort intervals by start time
Sorted intervals: [[0,30], [5,10], [15,20]]Step 2: Use min-heap to track earliest end time
Push 30; 5 < 30 -> push 10 (2 rooms); 15 >= 10 -> pop 10, push 20 (still 2 rooms)Final Answer:
Option B -> Option BQuick Check:
Heap size at end is 2 -> minimum rooms needed [OK]
Quick Trick: Heap size after processing = rooms needed [OK]
Common Mistakes:
MISTAKES- Not sorting intervals before heap usage
- Incorrect heap push/pop logic
Trap Explanation:
PITFALL- Candidates often forget to pop from heap when current start >= earliest end.
Interviewer Note:
CONTEXT- Tests ability to trace heap-based interval scheduling code.
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