1098. 城堡问题

方法BFS，flood fill，别被开头一张图给唬住了，对于每一个方格按位判断能不能走四个方向就行了

#include<iostream>
#include<queue>

using namespace std;

#define PII pair<int ,int>
#define x first
#define y second

const int N = 60;

int g[N][N];
int r, c;
int dx[] = {0, -1, 0, 1}, dy[] = {-1, 0, 1, 0}; // 西、北、东、南
int st[N][N];

int bfs(int x, int y){
    queue<PII> q;
    
    q.push({x, y});
    st[x][y] = 1;
    
    int ans = 1;
    
    while(q.size()){
        auto h = q.front();
        int x = h.x, y = h.y;
        q.pop();
        
        for(int i = 0; i < 4; i ++){
            int a = x + dx[i], b = y + dy[i];
            if(a < 0 || a >= r || b < 0 || b >= c || st[a][b]) continue;
            if(g[x][y] >> i & 1) continue;
            st[a][b] = 1;
            ans ++;
            q.push({a, b});
        }
    }
    
    return ans;
}

int main(){
    cin >> r >> c;
    
    for(int i = 0; i < r; i ++)
        for(int j = 0; j < c; j ++)
            cin >> g[i][j];
            
            
    int res = 0, cnt = 0;
    for(int i = 0; i < r; i ++)
        for(int j = 0; j < c; j ++){
            if(st[i][j] == 0){
                res = max(res, bfs(i, j));
                cnt ++;
            }
        }
    
    cout << cnt << endl;
    cout << res << endl;
    
    return 0;
}