将最后一个元素移到给定链表的前面 | 系列 2
原文：https://www.geeksforgeeks.org/move-last-element-to-front-of-a-given-linked-list-set-2/
给定一个单链表和一个整数K。 任务是将链表的最后K个元素附加到前面。
示例：
输入：
1 -> 2 -> 3 -> 4 -> 5 -> 6, k = 3输出：
4 -> 5 -> 6 -> 1 -> 2 -> 3输入：
1 -> 2 -> 3 -> 4 -> 5 -> 6, k = 7输出：
6 -> 1 -> 2 -> 3 -> 4 -> 5
先决条件：将最后一个元素移到给定链表的前面
方法：
-
循环
k % n次，其中n是链表中元素的数量。 -
每次，从链表的末尾删除一个节点。
-
同时在链表的开头插入该已删除的节点。
下面是上述方法的实现：
// CPP Program to move k last elements
// to front in a given linked list
#include<iostream>
using namespace std;
// A linked list node
class Node
{
public:
int data;
Node* next;
Node(int d) {
data = d;
next = NULL;
}
};
// Function to add a new node at the
// end/tail of Linked List
void insertAtTail(Node*& head, Node*& tail, int d ) {
Node* newnode = new Node(d);
if(tail == NULL) {
tail = head = newnode;
return;
}
tail->next = newnode;
tail = newnode;
}
// Function to add a node at the
// beginning of Linked List
void insertAtHead(Node*& head, Node*& tail,
Node*& deletedNode)
{
if(head == NULL) {
head = tail = deletedNode;
return;
}
deletedNode->next = head;
head = deletedNode;
return;
}
// Function to add a node at the beginning of Linked List
Node* deleteAtTail(Node*& head, Node*& tail) {
Node* deleted = tail;
Node* temp = head;
while(temp->next->next != NULL) {
temp = temp->next;
}
temp->next = NULL;
tail = temp;
return deleted;
}
// k can be more than n, so this function takes the modulus
// of k with n and delete nodes from end k
// times and simultaneously insert it in front
void appendAtFront(Node*& head, Node*& tail, int n, int k)
{
k = k % n;
while(k != 0) {
Node* deleted = deleteAtTail(head, tail);
insertAtHead(head, tail, deleted);
k--;
}
}
// Function to print nodes in a given linked list
void printLinkedList(Node* head) {
while(head != NULL) {
cout << head->data << " ";
head = head->next;
}
cout << endl;
}
// Driver Code
int main()
{
// Pointer to the start of the linked list
Node* head = NULL;
// Pointer to the end of the linked list
Node* tail = NULL;
// Number of elements in the linked list
int n = 6;
// Building linked list
insertAtTail(head, tail, 1);
insertAtTail(head, tail, 2);
insertAtTail(head, tail, 3);
insertAtTail(head, tail, 4);
insertAtTail(head, tail, 5);
insertAtTail(head, tail, 6);
// Printing linked list before
// appending the linked list
cout << "Linked List before appending: ";
printLinkedList(head);
// Number of elements to be appended
int k = 7;
// Function call
appendAtFront(head, tail, n, k);
// Printing linked list after appending the list
cout << "Linked List after appending "<<k<<" elements: ";
printLinkedList(head);
}
输出：
Linked List before appending: 1 2 3 4 5 6
Linked List after appending 7 elements: 6 1 2 3 4 5
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