leetcodequestion_56 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].

vector<Interval> merge(vector<Interval>& intervals) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
    	sort(intervals.begin(), intervals.end(), cmp);
		vector<Interval> res;
		vector<Interval>::iterator it = intervals.begin();
		Interval* cur = NULL;
		for(it; it != intervals.end(); ++it)
		{
            if(cur == NULL)
            {
                cur = &(*it);
				continue;
            }
			if((*cur).end < (*it).start)
			{
				res.push_back(*cur);
				cur = &(*it);
			}else{
				(*cur).end = (*cur).end > (*it).end ? (*cur).end : (*it).end;
			}
		}
		if(cur != NULL)
		res.push_back(*cur);
		return res;
    }