岛屿的最大面积

direction = [[1,0],[0,1],[-1,0],[0,-1]]
count = 0
def dfs(graph,visit,x,y):
    global count
    for i ,j in direction:
        curx = x+i
        cury = y+j
        if curx>=len(graph) or curx<0 or cury>=len(graph[0]) or cury<0:
            continue
        if graph[curx][cury] == 1 and visit[curx][cury] == False:
            visit[curx][cury] = True
            count += 1
            dfs(graph,visit,curx,cury)


n,m = map(int,input().split())
graph = []
for i in range(n):
    graph.append(list(map(int,input().split())))
visit = [[False]*m for _ in range(n)]
res = 0
for i in range(n):
    for j in range(m):
        if graph[i][j] == 1 and visit[i][j] == False:
            count = 1
            visit[i][j] = True
            dfs(graph,visit,i,j)
            res = max(res,count)
print(res)

错误写法如下：（待解决）

direction = [[1,0],[0,1],[-1,0],[0,-1]]
count = 0
def dfs(graph,visit,x,y):
    global count
    for i ,j in direction:
        curx = x+i
        cury = y+j
        if curx>=len(graph) or curx<0 or cury>=len(graph[0]) or cury<0:
            continue
        if graph[curx][cury] == 1 and visit[curx][cury] == False:
            visit[curx][cury] = True
            count += 1
            dfs(graph,visit,curx,cury)

def main():
    n,m = map(int,input().split())
    graph = []
    for i in range(n):
        graph.append(list(map(int,input().split())))
    visit = [[False]*m for _ in range(n)]
    res = 0
    for i in range(n):
        for j in range(m):
            if graph[i][j] == 1 and visit[i][j] == False:
                count = 1
                visit[i][j] = True
                dfs(graph,visit,i,j)
                res = max(res,count)
    print(res)
if __name__ == '__main__':
    main()

100. 岛屿的最大面积