Forest density

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

#define I_2D(row, col, width) ((row) * (width) + (col))
#define PRINT_ARR(arr, n)                                                      \
  do {                                                                         \
    for (int i = 0; i < n; i++) {                                              \
      cout << arr[i] << " ";                                                   \
    }                                                                          \
    cout << "\n";                                                              \
  } while (0)

typedef long long ll;

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);

  int n, q;
  cin >> n >> q;

  ll p_sum[n * n];
  char c;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) {
      cin >> c;
      if (c == '\n')
        cin >> c;
      p_sum[I_2D(i, j, n)] = c == '*' ? 1 : 0;

      if (i > 0) {
        p_sum[I_2D(i, j, n)] += p_sum[I_2D(i - 1, j, n)];
      }
      if (j > 0) {
        p_sum[I_2D(i, j, n)] += p_sum[I_2D(i, j - 1, n)];
      }
      if (j > 0 && i > 0) {
        p_sum[I_2D(i, j, n)] -= p_sum[I_2D(i - 1, j - 1, n)];
      }
    }
  }

  int y1, x1, y2, x2;
  ll s;
  for (int i = 0; i < q; i++) {
    cin >> y1 >> x1 >> y2 >> x2;
    --y1, --x1, --y2, --x2;
    s = p_sum[I_2D(y2, x2, n)];
    if (x1 > 0) {
      s -= p_sum[I_2D(y2, x1 - 1, n)];
    }
    if (y1 > 0) {
      s -= p_sum[I_2D(y1 - 1, x2, n)];
    }
    if (x1 > 0 && y1 > 0) {
      s += p_sum[I_2D(y1 - 1, x1 - 1, n)];
    }
    cout << s << endl;
  }

  return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED