アリ本 2-1 p35 Lake Counting

ant-2-1-p35.cpp

#include <iostream>
#include <algorithm>
#include <string>

using namespace std;

const int MAX_N = 100;
const int MAX_M = 100;

int N, M;
char field[MAX_N][MAX_M + 1];

void dfs(int x, int y)
{
  field[x][y] = '.';

  for (int dx = -1; dx <= 1; dx++)
  {
    for (int dy = -1; dy <= 1; dy++)
    {
      int nx = x + dx;
      int ny = y + dy;

      if (0 <= nx && nx <= N && 0 <= ny && ny <= M && field[nx][ny] == 'W')
        dfs(nx, ny);
    }
  }
  return;
}

void solve()
{
  int res = 0;
  for (int i = 0; i < N; i++)
  {
    for (int j = 0; j < M; j++)
    {
      if (field[i][j] == 'W')
      {
        dfs(i, j);
        res++;
      }
    }
  }
  cout << res << endl;
}

int main()
{
  ios::sync_with_stdio(false);
  cin >> N >> M;
  std::string s;
  for (int i = 0; i < N; i++)
  {
    cin >> s;
    for (int j = 0; j < M; j++)
    {
      field[i][j] = s[j];
    }
  }
  solve();
  return 0;
}