/**
 * 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) {
        vector<Interval> results;
        if (intervals.size() == 0) {
            return intervals;
        }

        sort(intervals.begin(), intervals.end(), [](Interval& a, Interval& b) {
           return tie(a.start, a.end) <= tie(b.start, b.end);
        });

        results.push_back(intervals[0]);
        auto prev = results[0];
        for(int i = 1; i< intervals.size(); ++i) {
            auto current = intervals[i];
            if (current.start <= prev.end) {
                results.pop_back();
                results.push_back(Interval(prev.start, max(prev.end, current.end)));
            }
            else {
                results.push_back(current);
            }
            prev = results[results.size() -1];
        }
        return results;
    }
};