leetcode 合并重叠区间变异 合并多个时间段 取并集

public class Solution  {
     public static ArrayList<Interval> merge(ArrayList<Interval> intervals) {
            ArrayList<Interval> result = new ArrayList<Interval>();
            if(intervals == null || intervals.size()==0)
                return result;
            Collections.sort(intervals,new IntervalComparator());
            Interval prev = intervals.get(0);
            for(int i=1;i<intervals.size();i++){
                Interval curr = intervals.get(i);
                if(prev.end>=curr.start){
                    Interval temp =new Interval(prev.start,Math.max(prev.end,curr.end));
                    prev = temp;
                }else{
                    result.add(prev);
                    prev = curr;
                }
            }
            result.add(prev);
            return result;
        }
    
     static class IntervalComparator implements Comparator<Interval>{
            public int compare(Interval s1,Interval s2){
                return (int) ((s1.start-s2.start)/24/3600/1000);
            }
        }
}

public class Interval {
    long start;
    long end;

    public long getStart() {
        return start;
    }

    public void setStart(long start) {
        this.start = start;
    }

    public long getEnd() {
        return end;
    }

    public void setEnd(long end) {
        this.end = end;
    }

    public Interval(long start, long end) {
        super();
        this.start = start;
        this.end = end;
    }

    public Interval() {
        super();
    }

}

int workDay = 0;
        for (Interval interval : list) {
            workDay += (interval.getEnd() - interval.getStart())/24/3600/1000;
        }