大佬帮我看看我这里哪有问题啊，感觉是和你的一样啊，为什么只有40%呢。
def solution(board):
for i in range(N-1, -1, -1):
for j in range(M):
if i == N-1:
if board[i][j] == '.' or board[i][j] == 'o':
board[i][j] = '.'
else:
continue
else:
if board[i][j] == 'x':
continue
elif board[i][j] == '.':
continue
else:
if board[i+1][j] == '.':
for k in range(i+2,N):
if board[k][j] == 'x' or board[k][j] == 'o':
board[k-1][j] = 'o'
board[i][j] = '.'
else:
continue
return board
N,M = map(int, input().split())
board = []
for i in range(N):
board.append(list(input()))
for row in solution(board):
print(''.join(row))
