NC14608 after与迷宫

\(bfs\)裸题，加两个\(bool\)变量判断下一步是否能继续走就好了

const int N=1010;
char g[N][N];
int dist[N][N];
struct Node
{
    int x,y;
    bool F,M;
};
PII ed;
int n,m;

inline bool check(int x,int y)
{
    return x>0 && x<=n && y>0 && y<=m;
}

int bfs(int x,int y)
{
    memset(dist,-1,sizeof dist);
    queue<Node> q;
    q.push({x,y,0,0});
    dist[x][y]=0;

    while(q.size())
    {
        Node t=q.front();
        int x=t.x,y=t.y;
        q.pop();
        
        if(x == ed.fi && y == ed.se) return dist[x][y];

        for(int i=0;i<4;i++)
        {
            int a=x+dx[i],b=y+dy[i];
            if(!check(a,b) || g[a][b] == '*') continue;
            

            Node nt={a,b,0,0};
            if(t.F) nt.F=true;
            if(t.M) nt.M=true;
            if(dist[a][b] == -1)
            {
                if(g[a][b] == 'F')
                {
                    if(nt.M) continue;
                    else nt.F=true;
                }
                if(g[a][b] == 'M')
                {
                    if(nt.F) continue;
                    else nt.M=true;
                }
                dist[a][b]=dist[x][y]+1;
                q.push(nt);
            }
        }
    }
    return -1;
}

int main()
{
    int T;
    cin>>T;
    while(T--)
    {
        cin>>n>>m>>ed.fi>>ed.se;

        for(int i=1;i<=n;i++) scanf("%s",g[i]+1);

        int t=bfs(1,1);

        if(~t) cout<<t*2<<endl;
        else puts("IMPOSSIBLE");
    }
    //system("pause");
}