链表及链表的逆置

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)

链表逆置

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)