1 #include<cstdio> 2 #include<algorithm> 3 #include<cstring> 4 #include<vector> 5 #include<queue> 6 #define N 400 7 using namespace std; 8 int t,n,m,dis[N][N],vis[N],dx[5]={1,0,-1,0}; 9 int dy[5]={0,1,0,-1}; 10 int d_cnt,ans,adj[N][N],V[N],live,tot,bf[N]; 11 char mp[N][N]; 12 queue <int> qx,qy; 13 inline int get(int x,int y) {return m*(x-1)+y;} 14 void add(int T) 15 { 16 for (int i=1;i<=n;i++) 17 for (int j=1;j<=m;j++) 18 for (int k=1;k<=d_cnt;k++) 19 if (mp[i][j]=='.' && dis[k][get(i,j)]<=T) 20 adj[k][get(i,j)]=1; 21 } 22 void BFS(int X,int Y) 23 { 24 ++d_cnt; 25 qx.push(X),qy.push(Y); 26 memset(vis,-1,sizeof(vis)); 27 vis[get(X,Y)]=0; 28 while (!qx.empty()) 29 { 30 int x=qx.front(),y=qy.front(); 31 for (int i=0;i<4;i++) 32 { 33 int xx=x+dx[i],yy=y+dy[i]; 34 if (mp[xx][yy]=='.' && vis[get(xx,yy)]==-1) 35 { 36 qx.push(xx),qy.push(yy); 37 vis[get(xx,yy)]=vis[get(x,y)]+1; 38 dis[d_cnt][get(xx,yy)]=vis[get(xx,yy)]; 39 } 40 } 41 qx.pop(),qy.pop(); 42 } 43 } 44 int find(int x) 45 { 46 for (int i=1;i<=n*m;i++) 47 { 48 if (!V[i] && adj[x][i]==1) 49 { 50 V[i]=1; 51 if (!bf[i] || find(bf[i])) 52 { 53 bf[i]=x; 54 return 1; 55 } 56 } 57 } 58 return 0; 59 } 60 void init() 61 { 62 memset(dis,127,sizeof(dis)); 63 memset(adj,0,sizeof(adj)); 64 memset(bf,0,sizeof(bf)); 65 d_cnt=0; 66 live=0; 67 ans=0; 68 } 69 int main() 70 { 71 scanf("%d",&t); 72 while (t--) 73 { 74 init(); 75 scanf("%d%d",&n,&m); 76 for (int i=1;i<=n;i++) 77 scanf("%s",mp[i]+1); 78 for (int i=1;i<=n;i++) 79 for (int j=1;j<=m;j++) 80 if (mp[i][j]=='D') 81 BFS(i,j); 82 else if (mp[i][j]=='.') live++; 83 for (int k=1;k<=150;k++) 84 { 85 add(k); 86 for (int i=1;i<=d_cnt;i++) 87 { 88 memset(V,0,sizeof(V)); 89 if (find(i)) ans++; 90 } 91 if (ans==live) 92 { 93 printf("%d ",k); 94 break; 95 } 96 } 97 if (ans!=live) 98 puts("impossible"); 99 } 100 return 0; 101 }