cr.cpp

/*              |\ | |  ||\ \ /(_~     |~)|_~|\/||_~|\/||~)|_~|~)
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                (J U S T   L I K E   E V E R Y O N E   E L S E !)

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*/                              
#include<bits/stdc++.h>
using namespace std;
 
#define fastio ios_base::sync_with_stdio(0); cin.tie(0)
#define LL long long 
#define mod 1000000007 
#define FOR(i, j, k) for (int i=j ; i<k ; i++)
#define ROF(i, j, k) for (int i=j ; i>=k ; i--) 
#define debug(...) fprintf(stderr, __VA_ARGS__), fflush(stderr)
#define time__(d) for(long blockTime = 0; (blockTime == 0 ? (blockTime=clock()) != 0 : false); debug("%s time : %.4fs", d, (double)(clock() - blockTime) / CLOCKS_PER_SEC))

const long long INF = 1e18;
const long long MAX = 1e5+10;
bool  pos; 
void f(vector<string>&v, int i, int j,int n,int m){
    if(i<0 || j>=m || i>=n || j<0) return;
    if(v[i][j]=='G') pos=false;
    if(v[i][j]=='.') v[i][j]='#';
}
void dfs(int i, int j , vector<vector<int>>&vis,vector<string>&v ,int n, int m,int &g){
    if(i<0 || j>=m || i>=n || j<0) return;
    if(vis[i][j]  || v[i][j]=='#') return;
    vis[i][j]=1; if(v[i][j]=='G') g++;
    int dx[] = {-1,1,0,0};
    int dy[] = {0,0,-1,1};
    FOR(k,0,4) 
        dfs(i+dx[k],j+dy[k],vis,v,n,m,g);
}
int main(){
    fastio;
    int t=1; cin>>t;
    while(t--){
        int n,m; cin>>n>>m; pos = true;
        vector<string>v(n);
        FOR(i,0,n) cin>>v[i]; int cnt = 0;
        FOR(i,0,n) {
            FOR(j,0,m){
                if(v[i][j]=='B') {
                    f(v,i-1,j,n,m);
                    f(v,i+1,j,n,m);
                    f(v,i,j-1,n,m);
                    f(v,i,j+1,n,m);
                } if(v[i][j]=='G') cnt++;
            }
        } 
        if(!pos) {cout<<"No\n"; continue;}
        vector<vector<int>>vis(n+1,vector<int>(m+1,0));
        FOR(i,0,n) {
            FOR(j,0,m){
                if(!vis[i][j] && v[i][j]=='G') {
                        int g=0;
                        dfs(i,j,vis,v,n,m,g); 
                        if(vis[n-1][m-1]==1)cnt-=g;
                    } 
                vis[n-1][m-1]=0;
            }
        }
     //   FOR(i,0,n) FOR(j,0,m )cout<<vis[i][j]<<" ";
        if(cnt==0) cout<<"Yes\n";
        else cout<<"No\n";
    }
}