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
     
       merge(vector
      
        &intervals) {13         if (intervals.size() < 2) return intervals;14         int len = intervals.size(), index = 0;15         vector
       
         result;16         vector
        
          left, right;17         for (Interval interval : intervals) {18             left.push_back(interval.start);19             right.push_back(interval.end);20         }21         sort(left.begin(), left.end());22         sort(right.begin(), right.end());23         while (index < len) {24             int s = left[index], e = right[index++];25             while (index < len) {26                 if (e >= left[index]) {27                     e = right[index++];28                 } else break;29             }30             result.push_back(Interval(s, e));31         }32         return result;33     }34 };
        
       
      
     

 

Also you can check this solution: http://fisherlei.blogspot.com/2013/04/leetcode-merge-intervals-solution.html