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].

Solution: 1. Sort in ascending order of 'start'.
2. Traverse the 'intervals', merge or push...

 1 /**
 2  * Definition for an interval.
 3  * struct 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 
11 bool compare(const Interval &a, const Interval &b) 
12 {
13     return a.start < b. start;
14 }
15 class Solution {
16 public:
17     
18     vector<Interval> merge(vector<Interval> &intervals) {
19         vector<Interval> res;
20         int N = intervals.size(); 
21         if(N <= 1) return intervals;
22         sort(intervals.begin(), intervals.end(), compare);
23         Interval last = intervals[0];
24         for(int i = 1; i < N; i++) {
25             if(intervals[i].start > last.end) {
26                 res.push_back(last);
27                 last = intervals[i];
28             }
29             else {
30                 last.end = max(last.end, intervals[i].end);
31             }
32         }
33         res.push_back(last);
34         return res;
35     }
36 };

 

posted @ 2014-04-16 07:31  beehard  阅读(124)  评论(0)  编辑  收藏  举报