24. Swap Nodes in Pairs leetcode Python 2016 new Season

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原创最新推荐文章于 2026-06-27 10:14:23 发布 498 阅读 AI 写同款· GEO 优化 ›

链表-LeetCode24. 两两交换链表中的节点（Python） ''' 给定 1->2->3->4, 你应该返回 2->1->4->3. 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。 ''' class ListNode(object): def __init__(self, x): self.val = x self.next = None class Solution(object): def swapPairs(self, head): """ :type head: ListNode 立即下载

Given a linked list, swap every two adjacent nodes and return its head.

For example,
Given 1->2->3->4, you should return the list as 2->1->4->3.

Your algorithm should use only constant space. You may not modify the values in the list, only nodes itself can be changed.

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# 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 not head or not head.next:
            return head
        dummyHead = pNode = ListNode(None)
        pNode.next = head
        while pNode.next and pNode.next.next:
            tmp = pNode.next.next
            pNode.next.next = tmp.next
            tmp.next = pNode.next
            pNode.next = tmp
            pNode = pNode.next.next
        return dummyHead.next