Given an array of meeting intervals [start, end], return the minimum number of rooms required.
Example 1
Input: intervals = [[0,30],[5,10],[15,20]]
Output: 2
Explanation: Two rooms are needed for overlapping intervals.
Output: 2
Explanation: Two rooms are needed for overlapping intervals.
Example 2
Input: intervals = [[7,10],[2,4]]
Output: 1
Explanation: The intervals do not overlap — one room is enough.
Output: 1
Explanation: The intervals do not overlap — one room is enough.