insert interval

/**
 * 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 comp(const pair<int, int>& p1, const pair<int, int>& p2)
{
    if(p1.first != p2.first)
    {
        return p1.first < p2.first;
    }

    return p1.second < p2.second;
} 

class Solution {
public:
    vector<Interval> insert(vector<Interval>& intervals, Interval newInterval) {
        vector<Interval> ret;
        int n = intervals.size();
        if(n == 0)
        {
            ret.push_back(newInterval);
            return ret;
        }

        intervals.push_back(newInterval);

    vector<pair<int, int>> time;
    for(Interval i : intervals)
    {
        time.push_back(make_pair(i.start, 0));
        time.push_back(make_pair(i.end, 1));
    }

    sort(time.begin(), time.end(), comp);

    int start = 0;
    int count = 0;
    for(pair<int, int> p : time)
    {
        if(p.second == 0)
        {
            count++;
            if(count == 1)
            {
                start = p.first;
            }
        }
        else
        {
            count--;
            if(count == 0)
            {
                ret.push_back(Interval(start, p.first));
            }
        }
    }

    return ret;
    }
};