def reverseKGroup(self, head, k):
if not head:
return
array = ListNode.toArray(head)
if len(array) == 0:
return
r = []
_len = len(array)
for i in range(0, _len, k):
if i + k > _len:
r += array[i: _len]
break
tmp = array[i:k+i]
tmp.reverse()
r += tmp
return ListNode.toList(r)
def main():
array = [1, 2]
head = ListNode.toList(array)
sln = Solution()
print(sln.reverseKGroup(head, 2).show())