样例和下载数据都没问题,但提交0分,求调.

#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=3e3+20;
int n,m,s,dx[]={0,1,0,-1},dy[]={1,0,-1,0},X,Y;
char cch,c[N][N];
bool vis[N][N],op;
inline int rd(){
	int s=0,w=1;char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-') w=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){s=s*10+ch-'0';ch=getchar();}
	return s*w;
}
bool check(int x,int y,int i){return (x+dx[i]>0&&y+dy[i]>0&&x+dx[i]<=n*2&&y+dy[i]<=m*2&&vis[x+dx[i]][y+dy[i]]==0&&(c[(x+dx[i]-1)%n+1][(y+dy[i]-1)%m+1]=='.'||c[(x+dx[i]-1)%n+1][(y+dy[i]-1)%m+1]=='S')?1:0);}
bool dfs(int x,int y){
	vis[x][y]=1;
	if((x!=X||y!=Y)&&c[(x-1)%n+1][(y-1)%m+1]=='S') return 1;
	for(int i=0;i<4;++i) if(check(x,y,i)) if(dfs(x+dx[i],y+dy[i])) return 1;
	return 0;
}
signed main(){
	while(1){
		cch=getchar();
		if(cch!='-'&&(cch<'0'||cch>'9')) break;
		s=1;n=m=0;
		while(cch<'0'||cch>'9'){if(cch=='-') s=-1;cch=getchar();}
		while(cch>='0'&&cch<='9') n=n*10+cch-'0',cch=getchar();
		n*=s;
		m=rd();
		for(int i=1;i<=n;++i){
			for(int j=1;j<=m;++j){
				c[i][j]=getchar();
				if(c[i][j]=='S') X=i,Y=j;
			}
			c[0][0]=getchar();
		}
		for(int i=1;i<=n*2;++i)
		    for(int j=1;j<=m*2;++j)
		        vis[i][j]=0;
//		cout<<n<<' '<<m<<'\n';
		cout<<(dfs(X,Y)?"Yes":"No")<<'\n';
	}
	return 0;
}