/**
 * 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:
    vector<Interval> merge(vector<Interval>& intervals) {
        int len = intervals.size();
        auto comp = [](const Interval& lhs, const Interval& rhs){return lhs.start < rhs.start;};
        sort(intervals.begin(), intervals.end(), comp);
        vector<Interval> res;
        for(int i = 0; i < len; ++i)
        {
            auto interval = intervals[i];
            if(res.empty())res.push_back(interval);
            else
            {
                auto last = res.back();
                if(interval.start > last.end)res.push_back(interval);
                else res.back().end = max(last.end, interval.end);
            }
        }
        return res;
    }
};