백준 2178번 파이썬 bfs easy

from collections import deque

n,m=map(int,input().split())

graph=[]

for _ in range(n):

    graph.append(list(map(int,input())))

def bfs(x,y):

    dx =[-1,1,0,0 ]

    dy=[0,0,1,-1]

    queue = deque()

    queue.append((x,y))

    while queue:

        x,y=queue.popleft()

        for i in range(4):

            nx=x+dx[i]

            ny=y+dy[i]

            if nx<0 or nx>=n or ny<0 or ny>=m:

                continue

            if graph[nx][ny]==1:

                graph[nx][ny]=graph[x][y]+1

                queue.append((nx,ny))

    return graph[n-1][m-1]

print(bfs(0,0))