链表-（翻转链表）的两种算法

常规方法:

# -*- coding:utf-8 -*-

""" 
Author: leadingme
Mail:[email protected]
MyWebsite:leadingme.top
"""

# 翻转链表
"""
    算法要求: 翻转一个单链表(不带头节点)
    示例:
        输入: 1->2->3->4->5->NULL
        输出: 5->4->3->2->1->NULL
"""

def reverseLinkList(head):
    """
    :param head:
    :return:head
    """
    valList = []
    pointer = head
    while pointer:  # 将链表的值依次取出
        valList.append(pointer.val)
        pointer = pointer.next
    pointer = head
    while valList:  # 将列表的值反向赋给链表的每个节点的val属性
        pointer.val = valList.pop()
        pointer = pointer.next
    return head

进阶方法:

def reserveLinkList2(head):
    """
    :param head:
    :return: head
    """
    if head is None:  # 链表为空
        return None
    Pre = Next = head
    if Next.next is None: # 链表只有一个头节点
        return head
    else:
        Pre = None
    while Next is not None:  # 详细图解可参考下方链接
        Next = Next.next
        head.next = Pre
        Per = head
        head = Next
    return head

详细图解参考链接戳这里