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].

　　

/**
 * Definition for an interval.
 * struct Interval {
 *     int start;
 *     int end;
 *     Interval() : start(0), end(0) {}
 *     Interval(int s, int e) : start(s), end(e) {}
 * };
 */
 
    bool sortM(const  Interval &a1, const  Interval &a2)
    {
      return a1.start < a2.start ;
    }
class Solution {
public:
   
    vector<Interval> merge(vector<Interval> &intervals) {
       
        int n = intervals.size();
        if(intervals.size() <2) return intervals;
        sort(intervals.begin(),intervals.end(),sortM);
        
        int i,max;
        Interval next,val = intervals[0]; 
        vector<Interval> result;
        
        for(i = 1; i< n; i++)
        {
            if(intervals[i].start > val.end){                 
                 result.push_back(val);
                 val = intervals[i] ;
            }else{
               val.end = val.end >intervals[i].end ? val.end : intervals[i].end;
            }
        } //end of for i
        result.push_back(val) ; 
        return result ;
      
    }
};