Interval 间隔问题

    public List<Interval> merge(List<Interval> intervals) {
        List<Interval> res = new ArrayList<>();
        if (intervals.size() == 0) return res;
        intervals.sort(new Comparator<Interval>() {
            @Override
            public int compare(Interval o1, Interval o2) {
                return o1.start - o2.start;
            }
        });
        int begin = intervals.get(0).start;
        int end = intervals.get(0).end;
        for (int i = 1; i < intervals.size(); i++) {
            if (end < intervals.get(i).start) {
                res.add(new Interval(begin, end));
                begin = intervals.get(i).start;
                end = intervals.get(i).end;
            }
            end = Math.max(end, intervals.get(i).end);
        }
        res.add(new Interval(begin, end));
        return res;
    }