HackerRank "Playing with numbers"

This is 'Difficult' - I worked out it within 45mins, and unlocked HackerRank Algorithm Level 80 yeah!

So the idea is straight forward:
1. sort the input array and calculate partial_sum()
2. find the negative\positive boundary with the accumulated given offset

Note: in C++ you have to use 'long long' type all the way. I will switch to Python later..

#include <cmath>
#include <cstdio>
#include <vector>
#include <queue>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <unordered_set>
using namespace std;

int main()
{
    int N, Q;

    //    Get Array
    cin >> N;
    vector<long long> v(N);
    for(int i = ; i < N; i ++)
        cin >> v[i];

    //    Some processing
    sort(v.begin(), v.end());
    vector<long long> pre(N);
    partial_sum(v.begin(), v.end(), pre.begin());

    //    Go Query
    long long off = ;
    cin >> Q;
    while(Q--)
    {
        long long tmp; cin >> tmp;
        off += tmp;

        auto it = lower_bound(v.begin(), v.end(), -off);
        long long cnt_neg = it - v.begin();
        long long cnt_pos = N - cnt_neg;

        long long sum_neg = llabs(off * cnt_neg + pre[cnt_neg - ]);
        long long sum_pos = llabs(off * cnt_pos + pre.back() - pre[cnt_neg - ]);

        cout << (sum_neg + sum_pos) << endl;
    }
    return ;
}