数据结构算法操作试题(C++/Python)——k个一组翻转链表

class Solution(object):
    def reverseKGroup(self, head, k):
        """
        :type head: ListNode
        :type k: int
        :rtype: ListNode
        """
        tmp_head = pre_head = ListNode(0)
        pre_head.next = head
        while self.judgekNode(tmp_head, k):
            i = k
            nextk_p = self.NodekNext(tmp_head, k + 1)
            while i != 1:
                self.NodekNext(tmp_head, i).next = tmp_head.next
                tmp_head.next = self.NodekNext(tmp_head, i)
                tmp_head = tmp_head.next
                i -= 1
            tmp_head = tmp_head.next
            tmp_head.next = nextk_p
        return pre_head.next
        
    def NodekNext(self, node, k):
        while k:
            node = node.next
            k -= 1
        return node
    
    def judgekNode(self, node, k):
        node = node.next
        while k:
            if not node: return False
            node = node.next
            k -= 1
        return True

class Solution(object):
	def reverseKGroup(self, head, k):           
        cnt = 0
        check = head
        while  cnt < k and check != None:
            cnt += 1
            check = check.next
        
        if cnt < k:
            return head
        
        point = head
        prev = self.reverseKGroup(check, k)
        while point != check:
            tmp = point.next
            point.next = prev
            prev = point
            point = tmp
        
        return prev