Problem

Given a list of intervals representing the start and end time of ‘N’ meetings, find the minimum number of rooms required to hold all the meetings.

Examples

Example 1:

Meetings: [ [1,4], [2,5], [7,9] ]
Output: 2
Explanation: Since [1,4] and [2,5] overlap, we need two rooms to hold these two meetings. [7,9] can
occur in any of the two rooms later.

Example 2:

Meetings: [ [6,7], [2,4], [8,12] ]
Output: 1
Explanation: None of the meetings overlap, therefore we only need one room to hold all meetings.

Example 3:

Meetings: [ [1,4], [2,3], [3,6] ]
Output: 2
Explanation: Since [1,4] overlaps with the other two meetings [2,3] and [3,6], we need two rooms to
hold all the meetings.

Example 4:

Meetings: [ [4,5], [2,3], [2,4], [3,5] ]
Output: 2
Explanation: We will need one room for [2,3] and [3,5], and another room for [2,4] and [4,5].

Solution

This problem is same as Maximum Intervals Overlap Count.