Meeting Rooms II.cpp

/**
 * Definition for an interval.
 * struct Interval {
 *     int start;
 *     int end;
 *     Interval() : start(0), end(0) {}
 *     Interval(int s, int e) : start(s), end(e) {}
 * };
 */
class Solution {
public:
    int minMeetingRooms(vector<Interval>& intervals) {
        vector<pair<int, int>> events;
        for(auto& interval : intervals)
        {
            events.push_back({interval.start, 1});
            events.push_back({interval.end, -1});
        }
        sort(events.begin(), events.end());
        int depth = 0, currD = 0;
        for(auto& event : events)
        {
            currD += event.second;
            depth = max(depth, currD);
        }
        return depth;
    }
};