很不錯的題 跟課程規劃那個題有點相似

bool cmp( const Interval& a , const Interval& b ) {
    if (a.start != b.start) return a.start < b.start;
    return a.end < b.end;
}

bool judge( Interval&a, Interval&b ) {
    if (a.end <= b.start || a.start >= b.end) return true;
    else return false;
}

class Solution {
public:
    int eraseOverlapIntervals(vector<Interval>& intervals) {
        if (intervals.size()<=1) return 0;
        sort( intervals.begin(), intervals.end(), cmp );
        Interval last = intervals[0];
        int ret = 0;
        for (int i = 1; i < intervals.size(); i++) {
            if (!judge(last, intervals[i])) {
                ret ++;
                if (last.end > intervals[i].end) last = intervals[i];
            } else {
                last = intervals[i];
            }
        }
        return  ret;
    }
};