Meeting Rooms II - Approach 1

Approach: Treat starts and ends as events. Count running meetings.

$1.$ Create events: (time, +1 for start, -1 for end).

$2.$ Sort by time. If tie, process end before start (a room freed is reusable).

$3.$ Scan events, track running count.

$4.$ Answer is maximum count seen. This counts how many meetings are happening simultaneously at each moment. The trick: processing end before start handles back-to-back meetings correctly. If meeting A ends at time $5$ and meeting B starts at time $5$, they can share a room.