IntervalsHeapSweep Line
Given a list of meetings with start and end times, find the minimum number of conference rooms needed so that all meetings can take place. A meeting ending at time t does not conflict with one starting at t.
Input
Line 1: n. Next n lines: the start and end of each meeting.
Output
Print the minimum number of rooms required.
Constraints
1 <= n <= 10^4 0 <= start < end <= 10^6
Example 1
Input
3 0 30 5 10 15 20
Output
2
0-30 overlaps both others, so two rooms are needed.
Example 2
Input
2 7 10 2 4
Output
1
One room is enough.