252.Meeting Rooms

1.Meeting-rooms https://leetcode.com/problems/meeting-rooms/
2.Meeting-rooms ii https://leetcode.com/problems/meeting-rooms-ii/

1.Meeting-rooms
https://leetcode.com/problems/meeting-rooms/
先排序再遍历

/**
 * 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:
    bool canAttendMeetings(vector<Interval>& intervals) {
        if(intervals.empty()) {
            return true;
        }
        sort(intervals.begin(),intervals.end(),[](Interval &a, Interval &b){ return a.start < b.start;});
        int last = intervals.front().end;
        for(int i = 1; i < intervals.size(); i++) {
            if(intervals[i].start < last) {
                return false;
            }
            last = intervals[i].end;
        }
        return true;
    }
};

2.Meeting-rooms ii https://leetcode.com/problems/meeting-rooms-ii/
计算最少需要多少个room。

class Solution {
public:
    int minMeetingRooms(vector<Interval>& intervals) {
        sort(intervals.begin(),intervals.end(), cmp);
        vector<int> rooms;
        bool noRoomFlag;
        for(auto &i: intervals) {
            noRoomFlag = true;
            for(auto &r: rooms){
                if(r <= i.start) { //<=
                    r = i.end;
                    noRoomFlag = false;
                    break;
                }
            }
            if(noRoomFlag) {
                rooms.push_back(i.end);
            }
        }
        return rooms.size();
    }

    static bool cmp(Interval &a, Interval &b) {
        return a.start < b.start || (a.start == b.start && a.end < b.end);
    }
};