from ListNode import ListNode
class Solution:
def swapPairs(self, head: ListNode) -> ListNode:
if head is None or head.next is None:
return head
l1 = ListNode(0)
l1.next = head
pf,p,q = l1,head,head.next
while p and q:
p.next = q.next
q.next = p
pf.next = q
pf = p
p = p.next
if p is None:
break
q = p.next
return l1.next
if __name__ == '__main__':
head = ListNode.initNodeList([1,2])
head = Solution().swapPairs(head)
ListNode.linkListPrint(head)
from ListNode import ListNode
class Solution:
def removeNthFromEnd(self, head: ListNode, n: int) -> ListNode:
if head is None:
return head
if head.next is None:
return None
p = head
q = None
count = 1
while p.next != None:
count += 1
p = p.next
p = head
if count is n:
return p.next
for i in range(count - n):
q = p
p = p.next
q.next = p.next
return head
if __name__ == '__main__':
arr = [1, 2]
head = ListNode.initNodeList(arr)
ListNode.linkListPrint(Solution().removeNthFromEnd(head, 2))
