LeetCode-24-Swap-Nodes-in-Pairs 链表递归水题

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
def swapPairs(self, head):
"""
:type head: ListNode
:rtype: ListNode
"""
if head==None:return None
if head.next==None:return head
nextHead=self.swapPairs(head.next.next)
h=head.next
h.next=head
h.next.next=nextHead
return h