Problem - Meeting Rooms II

Given an array of meeting intervals, find the minimum number of conference rooms required. Example: $[[0,30], [5,10], [15,20]]$ needs $2$ rooms.

At time 5, meetings $[0,30]$ and $[5,10]$ overlap. You're solving the maximum overlap count problem. At any point in time, how many intervals are active? Constraints: up to $10^4$ meetings.