BOJ 29634 - Hotel [C++]

문제

링크

풀이

#include <algorithm>
#include <iostream>
#include <vector>
using namespace std;
 
int dy[4] = {-1, 0, 1, 0};
int dx[4] = {0, 1, 0, -1};
 
int dfs(int n, int m, vector<vector<char>> &v, int y, int x) {
  int ret = 1;
  for (int i=0; i<4; i++) {
    int ny = y + dy[i], nx = x + dx[i];
    if (ny < 0 || ny >= n || nx < 0 || nx >= m || v[ny][nx] != '.') continue;
    v[ny][nx] = '*';
    ret += dfs(n, m, v, ny, nx);
  }
  return ret;
}
 
void solve(void) {
  int n, m; cin >> n >> m;
  vector<vector<char>> v(n, vector<char>(m));
  for (int i=0; i<n; i++) for (int j=0; j<m; j++) cin >> v[i][j];
 
  int ans = -1;
  for (int i=0; i<n; i++) for (int j=0; j<m; j++) {
    if (v[i][j] != '.') continue;
    v[i][j] = '*';
    ans = max(ans, dfs(n, m, v, i, j));
  }
  cout << ans;
}
 
int main(void) {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
 
  solve();
  return 0;
}