CountingRooms.cpp

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

int neighborX[4] = {0, 0, 1, -1};
int neighborY[4] = {1, -1, 0, 0};

int n, m, answer = 0;
int vis[1010][1010];
char grid[1010][1010];

bool isValid (int y, int x) {
  if (y < 0) return false;
  if (x < 0) return false;
  if (y >= n) return false;
  if (x >= m) return false;
  if (grid[y][x] == '#') return false;
  return true;
}

void DFS (int y, int x) {
  vis[y][x] = 1;
  for (int i = 0 ; i < 4 ; i++) {
    int newX = x + neighborX[i];
    int newY = y + neighborY[i];
    if (isValid(newY, newX)) {
      if (!vis[newY][newX]) {
        DFS(newY, newX);
      }
    }
  }
}

int main() {
    cin >> n >> m;
    for (int i = 0 ; i < n ; i++) {
      for (int j = 0 ; j < m ; j++) {
        cin >> grid[i][j];
        vis[i][j] = 0;
      }
    }
    for (int i = 0 ; i < n ; i++) {
      for (int j = 0 ; j < m ; j++) {
        if (grid[i][j] == '.' && !vis[i][j]) {
          DFS(i, j);
          answer++;
        }
      }
    }
    cout << answer << endl;
    return 0;
}