给定一个链表,两两交换其中相邻的节点,并返回交换后的链表。
你不能只是单纯的改变节点内部的值,而是需要实际的进行节点交换。
示例:
给定 1->2->3->4, 你应该返回 2->1->4->3.
来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/swap-nodes-in-pairs
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution:
def swapPairs(self, head: ListNode) -> ListNode:
if not head or not head.next:
return head
cur = dummy = ListNode(0)
dummy.next = head
while(dummy.next): #先删掉第一个节点再插到第二个节点后面
if dummy.next.next:
tmp = dummy.next
dummy.next = dummy.next.next
dummy = dummy.next
tmp1 = dummy.next
dummy.next = tmp
tmp.next = tmp1
dummy = dummy.next
else:
dummy = dummy.next
return cur.next