C++ solution with comments 19ms


  • 0
    Z
    /**
     * 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) {
            if (intervals.empty()) {
                return 0;
            }
            // Sort according to start time.
            sort(intervals.begin(), intervals.end(), [](const Interval &a, Interval &b) {
                return a.start < b.start;
            });
            // Top is min value, heap for the end times.
            priority_queue<int, vector<int>, greater<int>> end_times;
            end_times.push(intervals[0].end);
            for (int i = 1; i < intervals.size(); ++i) {
                const int end_t = intervals[i].end;
                const int start_t = intervals[i].start;
                if (start_t < end_times.top()) {
                    // Need a new room, as the next start time is earlier than the earliest end time.
                    end_times.push(end_t);
                } else {
                    // One room is available for the next start meeting, use that room instead.
                    end_times.pop();
                    end_times.push(end_t);
                }
            }
            // The size of the queue is the largest room used.
            return end_times.size();
        }
    };
    

Log in to reply
 

Looks like your connection to LeetCode Discuss was lost, please wait while we try to reconnect.