LeetCode 253 Meeting Rooms II - Problem Statement

Given meeting time intervals, find the minimum number of conference rooms required.

With intervals = [[0,30],[5,10],[15,20]]:

• Meeting [0,30] needs a room.
• At time 5, meeting [5,10] starts. [0,30] is ongoing. Need $2$ rooms.
• At time 15, meeting [15,20] starts. [0,30] still ongoing. Still $2$ rooms.
• Maximum concurrent: $2$ rooms.

With intervals = [[7,10],[2,4]]:

• [2,4] ends at 4. [7,10] starts at 7.
• Never overlapping. $1$ room suffices.

Constraints: $1 \le$ intervals.length $\le 10^4$.