Merge Intervals

/**
 * 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 Compare
{
public:
    bool operator () (const Interval& left, const Interval& right)
    {
        return left.start<right.start;    
    }
};
 
class Solution {
public:
    vector<Interval> merge(vector<Interval> &intervals) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        sort(intervals.begin(), intervals.end(), Compare());
        
        int len = intervals.size();
        vector<Interval> res;
        
        if (len <= 0)
        return res;
        
        res.push_back(intervals[0]);
        
        for (int i=1; i<len; ++i)
        {
            if (intervals[i].start<=(*(res.end()-1)).end)
            {
                Interval tmpI = *(res.end()-1);
                res.erase(res.end()-1);
                res.push_back(Interval(tmpI.start, max(intervals[i].end, tmpI.end)));
            }
            else
                res.push_back(intervals[i]);
        }
        
        return res;
    }
};