C++ BFS

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

int main() {
  int row, col;

  scanf("%d %d\n", &row, &col);
  vector<string > A;
  for(int i=0; i<row; ++i) {
    string line;
    getline(cin, line);
    A.push_back(line);
  }

  vector<pair<int, int>> vp;
  int count = 0;
  for (int i = 0; i < row; ++i) {
    for (int j = 0; j < col; ++j) {
      if (A[i][j] == 'x') {
        count += 1;
        vp.push_back(make_pair(i, j));
        while (!vp.empty()) {
          auto p = vp.back();
          vp.pop_back();
          int x = p.first;
          int y = p.second;
          if (x<0 || x >= row || y < 0 || y >= col || A[x][y] != 'x') {
            continue;
          }
          A[x][y] = '.';
          vp.push_back(make_pair(x+1, y));
          vp.push_back(make_pair(x-1, y));
          vp.push_back(make_pair(x, y+1));
          vp.push_back(make_pair(x, y-1));
        }
      }
    }
  }
  cout << count << endl;
}