LeetCode 0056 - Merge Intervals

/**
 * 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> res;
        if(intervals.empty())
            return res;
        sort(intervals.begin(), intervals.end(), [](Interval a, Interval b){return a.start < b.start;});
        res.push_back(intervals[0]);
        for(int i = 1; i < intervals.size(); i++){
            if(res.back().end < intervals[i].start)
                res.push_back(intervals[i]);
            else
                res.back().end = max(res.back().end, intervals[i].end);
        }
        return res;
    }
};