【第2题】 链表的逆置

链表是一个特殊的数据结构,其中每个节点包含自己的数据以及下一个值的引用(指针),链表的逆置就是指将链表下一个值的引用(指针)调换,如下图所示:

 

第一步 构造链表

class Node(object):

    def __init__(self, value, next):
        self.value = value
        self.next = next


head = Node('头', None)
last = head
for i in range(5):
    node = Node('v%s' % i, None)
    last.next = node
    last = node

# ######### 查看链表关系 ##########
print('原始链表信息为:')
print(head.value)
print(head.next.value)
print(head.next.next.value)
print(head.next.next.next.value)
print(head.next.next.next.next.value)
print(head.next.next.next.next.next.value)

第二步 链表逆置

实现思路:

 

实现代码:

def reverse_linked_list(head):
    """
    链表逆置
    :param head:
    :return:
    """
    if not head or not head.next:
        return head

    prev_node = None
    current_node = head
    next_node = head.next

    while True:
        current_node.next = prev_node
        if not next_node:
            break
        prev_node = current_node
        current_node = next_node
        next_node = current_node.next
    return current_node


new_head = reverse_linked_list(head)

print('逆置之后的链表')
print(new_head.value)
print(new_head.next.value)
print(new_head.next.next.value)
print(new_head.next.next.next.value)
print(new_head.next.next.next.next.value)
print(new_head.next.next.next.next.next.value)

  

 

posted @ 2019-09-28 16:15  武沛齐  阅读(1917)  评论(1编辑  收藏