Forest density

// ~/.vim/cpp_template.cpp
#include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
 
#define REP(i,a,b) for (int i = a; i < b; i++)
 
// Type Aliases for 1D and 2D vectors with initialization
#define vi(n, val) vector<int>(n, val) // 1D vector of ints with size n, initialized to val
#define vll(n, val) vector<long long>(n, val) // 1D vector of long longs with size n, initialized to val
#define ll long long
#define vvi(n, m, val) vector<vector<int>>(n, vector<int>(m, val)) // 2D vector of ints (n x m), initialized to val
#define vvll(n, m, val) vector<vector<long long>>(n, vector<long long>(m, val)) // 2D vector of long longs (n x m), initialized to val
 
 
using namespace std;
 
template <typename T>
void pV(const std::vector<T>& vec, const std::string& label = "Vector") {
    std::cout << label << ": [ ";
    for (const auto& elem : vec) {
        std::cout << elem << " ";
    }
    std::cout << "]" << std::endl;
}
 
 
using namespace std;
 
 
void dfs(int s, vector<bool> *visited, vector<int> (*adj)[]) {
    if ((*visited)[s]) return;
    (*visited)[s] = true;
    // process node s
 
 
    for (auto u: (*adj)[s]) {
        dfs(u, visited, adj);
    }
}
/*
vector<int> adj[N];                                                          
vector<bool> visited(N, false);
int u, v;
for(int i = 0; i < M;i++){
    cin >> u >> v;
    u--;
    v--;
    adj[u].push_back(v);
    adj[v].push_back(u);
}
*/
 
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    // Your code starts here
    int n, q;
    cin >> n >> q;
 
    vector<vector<int>> forest(n+1, vector<int>(n+1, 0));
    vector<vector<int>> fsum(n+1, vector<int>(n+1, 0));
 
    REP(i, 1, n+1){
        string s;
        cin >> s;
        REP(j, 0, n){
            forest[i][j+1] = s[j] == '*';
        }
    }
 
    // calc tree
    REP(i, 1, n+1){
        REP(j, 1, n+1){
            fsum[i][j] = forest[i][j] + fsum[i-1][j] + fsum[i][j-1] - fsum[i-1][j-1];
        }
    }
 
    // queries
    REP(i, 0, q){
        int y1, x1, y2, x2;
        cin >> y1 >> x1 >> y2 >> x2;
        cout << fsum[y2][x2] - fsum[y2][x1-1] - fsum[y1-1][x2] + fsum[y1-1][x1-1] << endl;
    }
 
    
    
    return 0;
}
 
 

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED