题解 | #合并区间#

public static ArrayList<Interval> merge(ArrayList<Interval> intervals) {
        intervals.sort(new Comparator<Interval>() {
            @Override
            public int compare(Interval o1, Interval o2) {
                return o1.start - o2.start;
            }
        });
        int j = 1;
        int i = 0;
        while (j < intervals.size()) {
            Interval before = intervals.get(i);
            Interval after = intervals.get(j);
            if (before.end >= after.start) {
                Interval tmp = new Interval(before.start, Math.max(before.end, after.end));
                intervals.remove(i); // 重点删除后，位置会往后移
                intervals.remove(i);
                intervals.add(i, tmp);  // 重点add, 不是set
            } else {
                i++;
                j++;
            }
        }
        return intervals;
    }