必关注

#include<bits/stdc++.h>
using namespace std;
int n,m;
char a[110][110];
void dfs(int x,int y){
	a[x][y]='#';
	if(a[x+1][y]=='.') dfs(x+1,y);
	if(a[x-1][y]=='.') dfs(x-1,y);
	if(a[x][y+1]=='.') dfs(x,y+1);
	if(a[x][y-1]=='.') dfs(x,y-1);
	return ;
}
int main(){
	cin>>n>>m;
	if(m>n)swap(m,n);
	for(int i=1;i<=m;i++)
		for(int j=1;j<=n;j++)
			cin>>a[i][j];
	dfs(1,1);
	if(a[m][n]=='#')cout<<"Yes";
	else cout<<"No";
	return 0;
}