Forest density

#include <bits/stdc++.h>
using namespace std;

// debug
template<class T> ostream& operator<<(ostream&, const vector<T>&);
template<class T> ostream& operator<<(ostream&, const set<T>&);
template<class T> ostream& operator<<(ostream&, const multiset<T>&);
template<class K, class V> ostream& operator<<(ostream&, const map<K, V>&);
template<class T, size_t N> ostream& operator<<(ostream&, const array<T, N>&);
template<class A, class B> ostream& operator<<(ostream& os, const pair<A, B>& p) { return os << "(" << p.first << ", " << p.second << ")"; }
template<class T>
void print_collection(ostream& os, const T& v) {
    os << "{";
    bool first = true;
    for (const auto& x : v) {
        if (!first) os << ", ";
        first = false;
        os << x;
    }
    os << "}";
}
template<class T> ostream& operator<<(ostream& os, const vector<T>& v) { print_collection(os, v); return os; }
template<class T> ostream& operator<<(ostream& os, const set<T>& v) { print_collection(os, v); return os; }
template<class T> ostream& operator<<(ostream& os, const multiset<T>& v) { print_collection(os, v); return os; }
template<class K, class V> ostream& operator<<(ostream& os, const map<K, V>& v) { print_collection(os, v); return os; }
template<class T, size_t N> ostream& operator<<(ostream& os, const array<T, N>& v) { print_collection(os, v); return os; }
#define dbg(x) cerr << #x << " = " << (x) << '\n'

using ll = long long;
constexpr int INF = 1'000'000'000; // 1e9
constexpr ll LINF = 1'000'000'000'000'000'000LL; // 1e18
constexpr int MOD = 1'000'000'007; // 1e9 + 7

inline ll add(ll a, ll b) { return (a + b) % MOD; }
inline ll sub(ll a, ll b) { return ((a - b) % MOD + MOD) % MOD; }
inline ll mul(ll a, ll b) { return (a * b) % MOD; }


void solve() {
    int n, q;
    cin >> n >> q;

    vector<vector<int>> x(n+1, vector<int>(n+1));
    string s;
    int sum;
    for(int i=1;i<=n;++i) {
        cin >> s;
        sum = 0;
        for(int j=1;j<=n;j++) {
            if(s[j-1]=='*') {
                sum++;
            }
            x[i][j] = x[i-1][j] + sum;
        }
    }

    // cout << x;
    
    int x1,x2,y1,y2;
    for(int i=0; i<q;++i) {
        cin >> y1 >>x1>>y2>>x2;

        cout << x[y2][x2] - x[y2][x1-1] - x[y1-1][x2] + x[y1-1][x1-1] << "\n";
    }
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    solve();

    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED