RE on #14，好奇自己什么地方写挂的。

码风可能不太美好。

#include<iostream>
#include<string>
#include<queue>

const int N = 5e2 + 5;
int n, m, s_x, s_y, e_x, e_y;
std::string a[N]; bool vis[N][N];

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

struct Node {int x, y; };

inline bool check1(int x, int y) {return x >= 1 && x <= n && y >= 1 && y <= m; }
inline bool check2(int x, int y) {return check1(x, y) && a[x][y] != '#' && !vis[x][y]; }
inline void push(std::queue<Node>& q, int x, int y) {
	q.push((Node){x, y}), vis[x][y] = true;
}

bool solve() {
	std::queue<Node> q; push(q, s_x, s_y);
	
	while(!q.empty()) {
		Node now = q.front(); q.pop();
		
		for(int i = 0; i < 4; ++i) {
			int now_x = now.x + dx[i], now_y = now.y + dy[i];
			if(!check2(now_x, now_y)) continue;
			if(now_x == e_x && now_y == e_y) return true;
			
			push(q, now_x, now_y);
		}
	}
	
	return false;
}

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(0), std::cout.tie(0);
	
	std::cin >> n >> m;
	for(int i = 1; i <= n; ++i) {
		for(int j = 1; j <= m; ++j) {
			std::cin >> a[i][j];
			
			if(a[i][j] == 's') s_x = i, s_y = j;
			if(a[i][j] == 'g') e_x = i, e_y = j;
		}
	}
	
	std::cout << (solve() ? "Yes" : "No");
	
	return 0;
}