下列代码为本题目的代码，结果为#6， #7 TLE，其余AC 目前没有想到任何其他优化的方法，求优化修改，谢谢！

#include <bits/stdc++.h>
using namespace std;

int n, m;
char board[1501][1501];
int metGrid[1501][1501][2];

const int dx[] = {1,0,-1,0};
const int dy[] = {0,1,0,-1};
const int dircount = 4;

inline int mod(int x, int n){
	return (x % n >= 0) ? x % n : (x % n + n);
}

void print(){
	for(int i=0; i<n; i++){
		for(int j=0; j<m; j++){
			cout << board[i][j];
		}
		cout << endl;
	}
	cout << endl;
}

int sx, sy;
bool DFS(int x, int y){
	int modx = mod(x,n), mody = mod(y,m);
	
	if(board[modx][mody] == 'X'){
		int lrx = metGrid[modx][mody][0];
		int lry = metGrid[modx][mody][1];

		int lx = x / n, ly =  y / m;
		return (lx != lrx || ly != lry);
	}
	else if(board[modx][mody] == '#'){
		return false;
	}
	else{
		board[modx][mody] = 'X';
		metGrid[modx][mody][0] = x / n; 
		metGrid[modx][mody][1] = y / m;
		
		for(int dir=0; dir<dircount; dir++){
			int newx = x + dx[dir], newy = y + dy[dir];	
			bool success = DFS(newx, newy);
			if(success) return true;
		}
		
		board[modx][mody] = '.';
		return false;
		
	}
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0); cout.tie(0);
	
	while(cin >> n >> m){
		for(int i=0; i<n; i++){
			for(int j=0; j<m; j++){
				cin >> board[i][j];
				if(board[i][j] == 'S'){
					sx = i, sy = j;
					board[i][j] = '.';
				}
			}
		}
		
		cout << (DFS(sx, sy) ? "Yes" : "No") << endl;
	}

	return 0;
}