import java.util.*;
public class Solution {
    public ArrayList<Interval> merge(ArrayList<Interval> intervals) {
        ArrayList<Interval> result = new ArrayList<>();
        if(intervals==null || intervals.size()==0){
            return result;
        }
        intervals.sort(Comparator.comparingInt(c -> c.start));
        result.add(intervals.get(0));
        for (int i = 1; i < intervals.size(); i++) {
            Interval cur = result.get(result.size()-1);
            if(cur.end<intervals.get(i).start){
                result.add(intervals.get(i));
            }else{
                cur.end = Math.max(cur.end,intervals.get(i).end);
            }
        }
        return result;
    }
}