LeetCode: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 private:
12      static bool cmp(const Interval& ina,const Interval& inb){
13         return ina.start < inb.start;
14     }
15     
16 public:
17     vector<Interval> merge(vector<Interval>& intervals) {
18         
19         vector<Interval> result;
20          int count = intervals.size();
21         if(count <= 1){
22             return intervals;
23         }
24         //先按start排序 
25         sort(intervals.begin(),intervals.end(),cmp);
26         // 合并  三种情况
27         result.push_back(intervals[0]);
28       
29        
30         for(int i = 1;i < count;i++){
31             Interval preIn = result.back();
32             Interval curIn = intervals[i];
33             if(curIn.start <= preIn.end && curIn.end > preIn.end){
34                    preIn.end = curIn.end;
35                    result.pop_back();
36                    result.push_back(preIn);
37             }
38             else if(curIn.start > preIn.end){
39                 result.push_back(curIn);
40             }
41         }
42         return result;
43         
44     }
45 };