class Solution {
public:
    bool canAttendMeetings(vector<Interval>& intervals) {
        sort(intervals.begin(), intervals.end(), compare);
        for(int i = 1; i < intervals.size(); ++i) {
            if(intervals[i-1].end > intervals[i].start ) return false;
        }
        return true;
    }
    private :
    static bool compare(Interval& it1, Interval& it2) {
        return it1.start < it2.start;
    }
};

• http://www.cnblogs.com/grandyang/p/5240774.html