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$ curl repovive.com/roadmaps/greedy-algorithms/interval-problems/meeting-rooms-ii-implementation

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$ curl repovive.com/roadmaps/greedy-algorithms/interval-problems/meeting-rooms-ii-implementation

Repovive

Meeting Rooms II - Implementation - Interval Problems | Greedy Algorithms | Repovive

Repovive.

Greedy Algorithms8 sections · 317 units14h total

Open in Course

Meeting Rooms II - Implementation

The code

Here is the solution using event sweep:

function minMeetingRooms(intervals)
 events := []
 for each interval in intervals
 events.add((interval.start, +1))
 events.add((interval.end, -1))
 sort events by time (if tie, process -1 before +1)
 rooms := 0
 maxRooms := 0
 for each (time, delta) in events
 rooms := rooms + delta
 maxRooms := max(maxRooms, rooms)
 return maxRooms

Time: $O(n \log n)$ . Space: $O(n)$ for events array.

The tie-breaking rule matters: if a meeting ends at time $t$ and another starts at $t$ , the ending frees a room before the new one needs it.