去括号
x=[[1, [1, 1]], 1, [1, 1]]
flatten(x)
[1, 1, 1, 1, 1, 1]
def flatten(lst):
list1=[]
for i in lst:
if type(i)==list:
list2=flatten(i)
list1+=list2#用这个将里面的list连接起来
else:
#print(i)
list1.append(i)
return list1