Forest density

#include <bits/stdc++.h>

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

    long n, q;
    std::cin >> n >> q;

    std::vector map(n + 1, std::vector(n+1, 0));

    for (long i = 1; i <= n; i++) {
        map[1][i] = map[1][i-1];
        char c;
        std::cin >> c;
        if (c == '*') {
            map[1][i]++;
        }
    }

    for (long y = 2; y <= n; y++) {
        for (long x = 1; x <= n; x++) {
            map[y][x] = map[y][x-1] + map[y-1][x] - map[y-1][x-1];
            char c;
            std::cin >> c;
            if (c == '*') {
                map[y][x]++;
            }
        }
    }

    for (long i = 0; i < q; i++) {
        long y1,x1,y2,x2;
        std::cin >> y1 >> x1 >> y2 >> x2;
        std::cout << (map[y2][x2] - map[y1 - 1][x2] - map[y2][x1 - 1] + map[y1 - 1][x1 - 1]) << std::endl;
    }

    std::cout << std::endl;
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED