【leetcode刷题笔记】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].

代码如下：

 1 /**
 2  * Definition for an interval.
 3  * public class Interval {
 4  *     int start;
 5  *     int end;
 6  *     Interval() { start = 0; end = 0; }
 7  *     Interval(int s, int e) { start = s; end = e; }
 8  * }
 9  */
10 public class Solution {
11     class IntervalComparator implements Comparator<Interval>{
12         public int compare(Interval a,Interval b){
13             return a.start - b.start;
14         }
15     }
16     public List<Interval> merge(List<Interval> intervals) {
17         if(intervals == null || intervals.size() <= 1)
18             return intervals;
19         Collections.sort(intervals,new IntervalComparator());
20
21         ArrayList<Interval> answer = new ArrayList<Interval>();
22
23         Interval last = intervals.get(0);
24         for(int i = 1;i < intervals.size();i++){
25             Interval now = intervals.get(i);
26             if(last.end >= now.start){
27                 last.end = Math.max(last.end, now.end);
28             }
29             else{
30                 answer.add(last);
31                 last = now;
32             }
33         }
34         answer.add(last);
35         return answer;
36
37
38     }
39 }

【leetcode刷题笔记】Merge Intervals