Merge Intervals

Given a collection of intervals, merge all overlapping intervals.

For example,
Given [1,3],[2,6],[8,10],[15,18],
return [1,6],[8,10],[15,18].

思路： 每一个Interval，要判断是否有前后相交

JAVA 代码：

1. public List<Interval> merge(List<Interval> intervals) {
2. Comparator comparator = new MyComparator();
3. Collections.sort(intervals,comparator);
4. List<Interval> res = new ArrayList<Interval>();
5. if(intervals==null) return res;
6. int lz = intervals.size();
7. if(lz==0) return res;
8. int i=0;
9. while(i<lz) {
10. int start=intervals.get(i).start;
11. int end=intervals.get(i).end;
12. while(i+1<lz && intervals.get(i+1).start<=end) {
13. end=Math.max(intervals.get(i+1).end,end);
14. i++;
15. }
16. res.add(new Interval(start,end));
17. i++;
18. }
19. return res;
20. }
21. public class MyComparator implements Comparator<Interval> {
22. public int compare(Interval emp1, Interval emp2){
23. return emp1.start - emp2.start;
24. }
25. }

可以考虑改进，不占用额外的空间。