Forest density

#include <algorithm>
#include <iostream>
#include <queue>
#include <vector>

using namespace std;

void preCalc(vector<vector<int> > v, vector<vector<int> >& aux) {
    int n = v.size();
    aux = v;

    for (int i = 1; i < n; i++)
        for (int j = 0; j < n; j++)
            aux[i][j] = v[i][j] + aux[i - 1][j];

    for (int i = 0; i < n; i++)
        for (int j = 1; j < n; j++)
            aux[i][j] += aux[i][j - 1];
}

int calc(vector<vector<int> >& aux, int tli, int tlj, int rbi,
         int rbj) {
    int sol = aux[rbi][rbj];

    if (tli > 0)
        sol -= aux[tli - 1][rbj];

    if (tlj > 0)
        sol -= aux[rbi][tlj - 1];

    if (tli > 0 && tlj > 0)
        sol += aux[tli - 1][tlj - 1];

    return sol;
}

int main() {
    // cin >> n >> m;
    // vector<vector<char> > map(n, vector<char>(m));
    // vector<vector<pair<int, int> > > path(n, vector<pair<int, int> >(m));
    int n, q;
    cin >> n >> q;
    vector<vector<int> > f(n, vector<int>(n));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            char x;
            cin >> x;
            if (x == '.')
                f[i][j] = 0;
            else
                f[i][j] = 1;
        }
    }

    vector<vector<int> > aux(n, vector<int>(n));

    preCalc(f, aux);

    for (int i = 0; i < q; i++) {
        int tli, tlj, rbi, rbj;
        cin >> tli >> tlj >> rbi >> rbj;
        cout << calc(aux, tli - 1, tlj - 1, rbi - 1, rbj - 1) << endl;
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED