[백준] 13565번 침투 python

import sys
sys.setrecursionlimit(10 ** 6)
n,m = map(int,sys.stdin.readline().split())
array = [list(map(int,sys.stdin.readline().strip())) for _ in range(n)]
visted = [[False]*m for _ in range(n)]
 
d = [[1,0],[0,1],[-1,0],[0,-1]]
def dfs(r,c):
    global flag
    if r>=n:
        flag=True
    if 0<=r<n and 0<=c<m and not visted[r][c] and array[r][c]==0:
        visted[r][c]=True
        for drc in d:
            dr = r + drc[0]
            dc = c + drc[1]
            dfs(dr,dc)
 
flag = False
for c in range(m):
    if array[0][c]==0:
        dfs(0,c)
 
if flag:
    print('YES')
else:
    print('NO')