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].

 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 class Solution {11 public:12     vector<Interval> merge(vector<Interval> &intervals) {13         vector<Interval> result;14         if(intervals.empty()) return result;15        16         sort(intervals.begin(),intervals.end(),cmp);17        18         int start=intervals[0].start;19         int end=intervals[0].end;20        21         for(int i=1;i<intervals.size();i++)22         {23             if(intervals[i].start<=end)24             {25                 //注意[1,4],[2,3]的情况26                 end=end<intervals[i].end?intervals[i].end:end;27             }28             else29             {30                 result.push_back(Interval(start,end));31                 start=intervals[i].start;32                 end=intervals[i].end;33             }34         }35  36         result.push_back(Interval(start,end));37         return result;38     }39    40     static int cmp(const Interval &a,const Interval &b)41     {42         if(a.start<b.start) return 1;43         else if(a.start>b.start) return 0;44         else return a.end<b.end;45     }46 };