python dfs

from typing import List
class Solution:
    def main(self, sx:int, sy:int, ex:int, ey:int, n: int, G:List[List[int]]):
        dirs=[[-1, 0], [0, 1], [1, 0], [0, -1]]
        vis = [[False for _ in range(n)] for _ in range(n)]
        def dfs(x, y):
            if G[x][y]=='#': return False
            if x==ex and y==ey: return True
            vis[x][y]=True
            for d in dirs:
                nx, ny = x+d[0], y+d[1]
                if 0<=nx and nx<n and 0<=ny and ny<n and not vis[nx][ny] and G[nx][ny]=='.':
                    if dfs(nx, ny): return True
            return False
        if dfs(sx, sy): print("YES")
        else: print("NO")



if __name__ == '__main__':
    T=int(input())
    sol=Solution()
    for _ in range(T):
        n=int(input())
        G=[[] for _ in range(n)]
        for i in range(n):
            G[i]=list(map(str, input()))
        sx, sy, ex, ey = map(int, input().split())
        sol.main(sx, sy, ex, ey, n, G)

c++ dfs

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

const int N=105;

int n, T;
char G[N][N];
bool vis[N][N];
const int dirs[4][2]={{-1, 0}, {0, 1}, {1, 0}, {0, -1}};
int xa, ya, xb, yb;

bool dfs(int x, int y){
    if(G[x][y]=='#') return false;
    if(x==xb && y==yb) return true;
    vis[x][y]=true;
    for(int i=0; i<4; ++i){
        int nx=x+dirs[i][0];
        int ny=y+dirs[i][1];
        if(0<=nx && nx<n && 0<=ny &&ny<n && !vis[nx][ny] && G[nx][ny]=='.'){
            if(dfs(nx, ny)) return true;
        } 
    }
    return false;
}


int main(){
    cin>>T;
    while(T--){
        cin>>n;
        for(int i=0; i<n; ++i) cin>>G[i];
        memset(vis, 0x00, sizeof vis);
        cin>>xa>>ya>>xb>>yb;
        if(dfs(xa, ya)) cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }

    return 0;
}