Leetcode | Merge Intervals

class Solution {
public:
    static bool comp(Interval m1, Interval m2) {
        return m1.start < m2.start;
    }

    vector<Interval> merge(vector<Interval> &intervals) {
        sort(intervals.begin(), intervals.end(), Solution::comp);
        vector<Interval> ret;
        if (intervals.empty()) return ret;
        Interval pre(intervals[0]);
        for (int i = 0; i < intervals.size(); ++i) {
            if (intervals[i].start <= pre.end) {
                if (intervals[i].end > pre.end) pre.end = intervals[i].end;
            } else {
                ret.push_back(pre);
                pre = intervals[i];
            }
        }
        ret.push_back(pre);
        
        return ret;
    }
};