p56

 

 * Definition for an interval.
 * public class Interval {
 *     int start;
 *     int end;
 *     Interval() { start = 0; end = 0; }
 *     Interval(int s, int e) { start = s; end = e; }
 * }
 */
public class  {
    public List<Interval> merge(List<Interval> intervals) {
        List<Interval> ans = new ArrayList<Interval>();
		if (intervals.size() < 1)
			return ans;
		Collections.sort(intervals, new Comparator<Interval>() {
			
			public int compare(Interval a, Interval b) {
				return (int) (a.start - b.start);
			}
		});

		int start = intervals.get(0).start;
		int end = intervals.get(0).end;

		for (int i = 0; i < intervals.size() ; i++) {

			if (end >= intervals.get(i).start) {
				end = Math.max(intervals.get(i).end, end);

			} else {
				ans.add(new Interval(start, end));
				start = intervals.get(i).start;
				end = intervals.get(i).end;
			}
		}
		ans.add(new Interval(start, end));
		return ans;
    }
}