用于将最后一个元素移动到给定链表前面的Java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。
- 使倒数第二个倒数第二个(secLast->next = NULL)。
- 将最后一个的下一个设置为头(last->next = *head_ref)。
- 将最后一个作为头部(*head_ref = last)。
Java
/* Java Program to move last element to
front in a given linked list */
class LinkedList
{
// Head of list
Node head;
// Linked list Node
class Node
{
int data;
Node next;
Node(int d)
{
data = d;
next = null;
}
}
void moveToFront()
{
/* If linked list is empty or
it contains only one node
then simply return. */
if(head == null ||
head.next == null)
return;
/* Initialize second last and
last pointers */
Node secLast = null;
Node last = head;
/* After this loop secLast contains
address of second last node and
last contains address of last node
in Linked List */
while (last.next != null)
{
secLast = last;
last = last.next;
}
// Set the next of second last as null
secLast.next = null;
// Set the next of last as head
last.next = head;
// Change head to point to
// last node.
head = last;
}
// Utility functions
/* Inserts a new Node at front
of the list. */
public void push(int new_data)
{
/* 1 & 2: Allocate the Node &
Put in the data*/
Node new_node = new Node(new_data);
// 3. Make next of new Node as head
new_node.next = head;
// 4. Move the head to point to
// new Node
head = new_node;
}
// Function to print linked list
void printList()
{
Node temp = head;
while(temp != null)
{
System.out.print(temp.data + " ");
temp = temp.next;
}
System.out.println();
}
// Driver code
public static void main(String args[])
{
LinkedList llist = new LinkedList();
/* Constructed Linked List is
1->2->3->4->5->null */
llist.push(5);
llist.push(4);
llist.push(3);
llist.push(2);
llist.push(1);
System.out.println(
"Linked List before moving last to front ");
llist.printList();
llist.moveToFront();
System.out.println(
"Linked List after moving last to front ");
llist.printList();
}
}
// This code is contributed by Rajat Mishra
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!