[이코테 DFS]음료수 얼려먹기

https://www.youtube.com/watch?v=7C9RgOcvkvo&list=PLRx0vPvlEmdAghTr5mXQxGpHjWqSz0dgC&index=3 

def dfs(x,y,graph):
    if x < 0 or x >= n or y < 0 or y >= m:
        return
    if graph[x][y] == 1:
        return False
    else:
        graph[x][y] = 1
        dfs(x-1,y,graph)
        dfs(x+1,y,graph)
        dfs(x,y-1,graph)
        dfs(x,y+1,graph)
    return True
from collections import deque

n,m = map(int,input().split())
graph=[]
cnt = 0
for i in range(n):
    graph.append(list(map(int,input())))

for i in range(n):
    for j in range(m):
        if dfs(i,j,graph):
            cnt += 1
#print(graph)
#print(n,m)
print(cnt)