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) {}
 * };
 */
class Solution {
private:
     static bool cmp(const Interval& ina,const Interval& inb){
        return ina.start < inb.start;
    }
    
public:
    vector<Interval> merge(vector<Interval>& intervals) {
        
        vector<Interval> result;
         int count = intervals.size();
        if(count <= 1){
            return intervals;
        }
        //先按start排序 
        sort(intervals.begin(),intervals.end(),cmp);
        // 合并  三种情况
        result.push_back(intervals[0]);
      
       
        for(int i = 1;i < count;i++){
            Interval preIn = result.back();
            Interval curIn = intervals[i];
            if(curIn.start <= preIn.end && curIn.end > preIn.end){
                   preIn.end = curIn.end;
                   result.pop_back();
                   result.push_back(preIn);
            }
            else if(curIn.start > preIn.end){
                result.push_back(curIn);
            }
        }
        return result;
        
    }
};