Meeting Rooms II Solution

Implement either the event sweep or heap approach. Both give the same answer. The event sweep is more intuitive.

The heap approach extends better to variations like "assign meetings to specific rooms." Edge cases:

• No meetings: return 0
• Single meeting: return 1
• All meetings sequential: return 1
• All meetings overlap: return $n$

Time: $O(n \log n)$. Space: $O(n)$.