Laptop Rentals

• Time : O(nlogn)
• Space : O(n)

int laptopRentals(vector<vector<int>> T) {
    sort(begin(T), end(T));
    int res = 0;
    priority_queue<int, vector<int>, greater<int>> pq;
    for(auto t : T) {
        res = max(res, (int)pq.size());
        int s = t[0], e = t[1];
        while(!pq.empty() and pq.top() <= s) pq.pop();
        pq.push(e);
    }
    return max(res, (int)pq.size());
}