用于将最后一个元素移动到给定链接列表前面的Python程序

编写一个函数，将给定单链表中的最后一个元素移到前面。例如，如果给定的链表是 1->2->3->4->5，那么函数应该将链表更改为 5->1->2->3->4。
算法：
遍历列表直到最后一个节点。使用两个指针：一个存储最后一个节点的地址，另一个存储倒数第二个节点的地址。循环结束后进行以下操作。

1. 使倒数第二个倒数第二个（secLast->next = NULL）。
2. 将最后一个的下一个设置为头（last->next = *head_ref）。
3. 将最后一个作为头部（*head_ref = last）。

Python3

# Python3 code to move the last item 
# to front
class Node:
    def __init__(self, data):
        self.data = data
        self.next = None
  
class LinkedList:
    def __init__(self):
        self.head = None
  
    # Function to add a node 
    # at the beginning of Linked List
    def push(self, data):
        new_node = Node(data)
        new_node.next = self.head
        self.head = new_node
          
    # Function to print nodes in 
    # a given linked list
    def printList(self):
        tmp = self.head
        while tmp is not None:
            print(tmp.data, end = ", ")
            tmp = tmp.next
        print()
  
    # Function to bring the last node 
    # to the front
    def moveToFront(self):
        tmp = self.head
  
        # To maintain the track of
        # the second last node
        sec_last = None 
  
        # To check whether we have not 
        # received the empty list or list 
        # with a single node
        if not tmp or not tmp.next: 
            return
  
        # Iterate till the end to get
        # the last and second last node 
        while tmp and tmp.next :
            sec_last = tmp
            tmp = tmp.next
  
        # Point the next of the second
        # last node to None
        sec_last.next = None
  
        # Make the last node as the 
        # first Node
        tmp.next = self.head
        self.head = tmp
  
# Driver Code
if __name__ == '__main__':
    llist = LinkedList()
      
    # Swap the 2 nodes
    llist.push(5)
    llist.push(4)
    llist.push(3)
    llist.push(2)
    llist.push(1)
    print (
    "Linked List before moving last to front ")
    llist.printList()
    llist.moveToFront()
    print (
    "Linked List after moving last to front ")
    llist.printList()

输出：

Linked list before moving last to front 
1 2 3 4 5 
Linked list after removing last to front 
5 1 2 3 4

时间复杂度： O(n)，其中 n 是给定链表中的节点数。

有关详细信息，请参阅有关将最后一个元素移动到给定链接列表前面的完整文章！