数据结构:如何实现链表插入节点?详细实现代码

2021年3月19日14:08:14 发表评论 784 次浏览

本文概述

我们在上一篇文章中已经介绍了链表。我们还创建了一个包含3个节点的简单链表,并讨论了链表遍历。

本文讨论的所有程序均考虑以下链表的表示形式。

C ++

// A linked list node 
class Node 
{ 
     public :
     int data; 
     Node *next; 
}; 
// This code is contributed by rathbhupendra

C

// A linked list node
struct Node
{
   int data;
   struct Node *next;
};

Java

// Linked List Class
class LinkedList
{
     Node head;  // head of list
  
     /* Node Class */
     class Node
     {
         int data;
         Node next;
           
         // Constructor to create a new node
         Node( int d) {data = d; next = null ; }
     }
}

python

# Node class
class Node:
  
     # Function to initialize the node object
     def __init__( self , data):
         self .data = data  # Assign data
         self . next = None  # Initialize next as null
  
# Linked List class
class LinkedList:
    
     # Function to initialize the Linked List object
     def __init__( self ): 
         self .head = None

C#

/* Linked list Node*/
public class Node
{
     public int data;
     public Node next;
     public Node( int d) {data = d; next = null ; }
}

在这篇文章中, 讨论了在链表中插入新节点的方法。可以通过三种方式添加节点

1)

在链接列表的最前面

2)

在给定节点之后。

3)

在链接列表的末尾。

推荐:请在"

实践

首先, 在继续解决方案之前。

在前面添加一个节点:(4个步骤)

新节点始终添加在给定链接列表的开头之前。新添加的节点成为链接列表的新头。例如, 如果给定的链接列表为10-> 15-> 20-> 25, 并且我们在前面添加了项目5, 则链接列表将变为5-> 10-> 15-> 20-> 25。让我们将添加到列表最前面的函数称为push()。 push()必须接收一个指向head指针的指针, 因为push必须更改head指针以指向新节点(请参见

这个

)

linkedlist_insert_at_start

以下是在最前面添加节点的4个步骤。

C ++

/* Given a reference (pointer to pointer) 
to the head of a list and an int, inserts a new node on the front of the list. */
void push(Node** head_ref, int new_data) 
{ 
     /* 1. allocate node */
     Node* new_node = new Node(); 
  
     /* 2. put in the data */
     new_node->data = new_data; 
  
     /* 3. Make next of new node as head */
     new_node->next = (*head_ref); 
  
     /* 4. move the head to point to the new node */
     (*head_ref) = new_node; 
} 
  
// This code is contributed by rathbhupendra

C

/* Given a reference (pointer to pointer) to the head of a list
    and an int, inserts a new node on the front of the list. */
void push( struct Node** head_ref, int new_data)
{
     /* 1. allocate node */
     struct Node* new_node = ( struct Node*) malloc ( sizeof ( struct Node));
   
     /* 2. put in the data  */
     new_node->data  = new_data;
   
     /* 3. Make next of new node as head */
     new_node->next = (*head_ref);
   
     /* 4. move the head to point to the new node */
     (*head_ref)    = new_node;
}

Java

/* This function is in LinkedList class. Inserts a
    new Node at front of the list. This method is 
    defined inside LinkedList class shown above */
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;
}

python

# This function is in LinkedList class
# Function to insert a new node at the beginning
def push( self , new_data):
  
     # 1 & 2: Allocate the Node &
     #        Put in the data
     new_node = Node(new_data)
          
     # 3. Make next of new Node as head
     new_node. next = self .head
          
     # 4. Move the head to point to new Node 
     self .head = new_node

C#

/* 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;
}

push()的时间复杂度为O(1), 因为它要做的工作量是恒定的。

在给定节点之后添加节点:(5个步骤的过程)

我们获得了指向节点的指针, 并且在给定节点之后插入了新节点。

linkedlist_insert_middle

C ++

// Given a node prev_node, insert a 
// new node after the given  
// prev_node
void insertAfter(Node* prev_node, int new_data)  
{
    
     // 1. Check if the given prev_node is NULL 
     if (prev_node == NULL)  
     {  
         cout << "the given previous node cannot be NULL" ;  
         return ;  
     } 
    
     // 2. Allocate new node
     Node* new_node = new Node(); 
    
     // 3. Put in the data 
     new_node->data = new_data;  
    
     // 4. Make next of new node as 
     // next of prev_node 
     new_node->next = prev_node->next;  
    
     // 5. move the next of prev_node
     // as new_node 
     prev_node->next = new_node;  
} 
  
// This code is contributed by anmolgautam818

C

/* Given a node prev_node, insert a new node after the given 
prev_node */
void insertAfter( struct Node* prev_node, int new_data) 
{ 
     /*1. check if the given prev_node is NULL */
     if (prev_node == NULL) 
     { 
     printf ( "the given previous node cannot be NULL" );     
     return ; 
     } 
          
     /* 2. allocate new node */
     struct Node* new_node =( struct Node*) malloc ( sizeof ( struct Node)); 
  
     /* 3. put in the data */
     new_node->data = new_data; 
  
     /* 4. Make next of new node as next of prev_node */
     new_node->next = prev_node->next; 
  
     /* 5. move the next of prev_node as new_node */
     prev_node->next = new_node; 
}

Java

/* This function is in LinkedList class. 
Inserts a new node after the given prev_node. This method is 
defined inside LinkedList class shown above */
public void insertAfter(Node prev_node, int new_data) 
{ 
     /* 1. Check if the given Node is null */
     if (prev_node == null ) 
     { 
         System.out.println( "The given previous node cannot be null" ); 
         return ; 
     } 
  
     /* 2. Allocate the Node & 
     3. Put in the data*/
     Node new_node = new Node(new_data); 
  
     /* 4. Make next of new Node as next of prev_node */
     new_node.next = prev_node.next; 
  
     /* 5. make next of prev_node as new_node */
     prev_node.next = new_node; 
}

python

# This function is in LinkedList class. 
# Inserts a new node after the given prev_node. This method is 
# defined inside LinkedList class shown above */ 
def insertAfter( self , prev_node, new_data): 
  
     # 1. check if the given prev_node exists 
     if prev_node is None : 
         print "The given previous node must inLinkedList."
         return
  
     # 2. Create new node & 
     # 3. Put in the data 
     new_node = Node(new_data) 
  
     # 4. Make next of new Node as next of prev_node 
     new_node. next = prev_node. next
  
     # 5. make next of prev_node as new_node 
     prev_node. next = new_node

C#

/* Inserts a new node after the given prev_node. */
public void insertAfter(Node prev_node, int new_data) 
{ 
     /* 1. Check if the given Node is null */
     if (prev_node == null ) 
     { 
         Console.WriteLine( "The given previous node" + 
                                 " cannot be null" ); 
         return ; 
     } 
  
     /* 2 & 3: Allocate the Node & 
             Put in the data*/
     Node new_node = new Node(new_data); 
  
     /* 4. Make next of new Node as 
                 next of prev_node */
     new_node.next = prev_node.next; 
  
     /* 5. make next of prev_node 
                     as new_node */
     prev_node.next = new_node; 
}

insertAfter()的时间复杂度为O(1), 因为它的工作量是恒定的。

在最后添加一个节点:(6个步骤的过程)

新节点始终添加在给定链接列表的最后一个节点之后。例如, 如果给定的链接列表为5-> 10-> 15-> 20-> 25, 并且我们在末尾添加了项目30, 则链接列表将变为5-> 10-> 15-> 20-> 25- > 30。

由于链接列表通常由其头部表示, 因此我们必须遍历该列表直至结束, 然后将最后一个节点的下一个更改为新节点。

linkedlist_insert_last

以下是最后添加节点的6个步骤。

C ++

// Given a reference (pointer to pointer) to the head  
// of a list and an int, appends a new node at the end 
void append(Node** head_ref, int new_data)  
{  
    
     // 1. allocate node 
     Node* new_node = new Node(); 
    
     // Used in step 5 
     Node *last = *head_ref; 
    
     // 2. Put in the data 
     new_node->data = new_data;  
    
     // 3. This new node is going to be  
     // the last node, so make next of  
     // it as NULL
     new_node->next = NULL;  
    
     // 4. If the Linked List is empty, // then make the new node as head 
     if (*head_ref == NULL)  
     {  
         *head_ref = new_node;  
         return ;  
     }  
    
     // 5. Else traverse till the last node 
     while (last->next != NULL)  
         last = last->next;  
    
     // 6. Change the next of last node 
     last->next = new_node;  
     return ;  
}  
  
// This code is contributed by anmolgautam818

C

/* Given a reference (pointer to pointer) to the head
    of a list and an int, appends a new node at the end  */
void append( struct Node** head_ref, int new_data)
{
     /* 1. allocate node */
     struct Node* new_node = ( struct Node*) malloc ( sizeof ( struct Node));
  
     struct Node *last = *head_ref;  /* used in step 5*/
   
     /* 2. put in the data  */
     new_node->data  = new_data;
  
     /* 3. This new node is going to be the last node, so make next 
           of it as NULL*/
     new_node->next = NULL;
  
     /* 4. If the Linked List is empty, then make the new node as head */
     if (*head_ref == NULL)
     {
        *head_ref = new_node;
        return ;
     }  
       
     /* 5. Else traverse till the last node */
     while (last->next != NULL)
         last = last->next;
   
     /* 6. Change the next of last node */
     last->next = new_node;
     return ;    
}

Java

/* Appends a new node at the end.  This method is 
    defined inside LinkedList class shown above */
public void append( int new_data)
{
     /* 1. Allocate the Node &
        2. Put in the data
        3. Set next as null */
     Node new_node = new Node(new_data);
  
     /* 4. If the Linked List is empty, then make the
            new node as head */
     if (head == null )
     {
         head = new Node(new_data);
         return ;
     }
  
     /* 4. This new node is going to be the last node, so
          make next of it as null */
     new_node.next = null ;
  
     /* 5. Else traverse till the last node */
     Node last = head; 
     while (last.next != null )
         last = last.next;
  
     /* 6. Change the next of last node */
     last.next = new_node;
     return ;
}

python

# This function is defined in Linked List class
# Appends a new node at the end.  This method is
#  defined inside LinkedList class shown above */
def append( self , new_data):
 
    # 1. Create a new node
    # 2. Put in the data
    # 3. Set next as None
    new_node = Node(new_data)
 
    # 4. If the Linked List is empty, then make the
    #    new node as head
    if self .head is None :
         self .head = new_node
         return
 
    # 5. Else traverse till the last node
    last = self .head
    while (last. next ):
        last = last. next
 
    # 6. Change the next of last node
    last. next =  new_node

C#

/* Appends a new node at the end. This method is 
defined inside LinkedList class shown above */
public void append( int new_data)
{
     /* 1. Allocate the Node &
     2. Put in the data
     3. Set next as null */
     Node new_node = new Node(new_data);
  
     /* 4. If the Linked List is empty, then make the new node as head */
     if (head == null )
     {
         head = new Node(new_data);
         return ;
     }
  
     /* 4. This new node is going to be 
     the last node, so make next of it as null */
     new_node.next = null ;
  
     /* 5. Else traverse till the last node */
     Node last = head; 
     while (last.next != null )
         last = last.next;
  
     /* 6. Change the next of last node */
     last.next = new_node;
     return ;
}

append的时间复杂度为O(n), 其中n是链表中节点的数量。由于从头到尾都有一个循环, 因此该函数可以执行O(n)。

通过保留指向链接列表/尾部的额外指针, 还可以将该方法优化为在O(1)中工作

以下是使用上述所有方法来创建链接列表的完整程序。

C ++

// A complete working C++ program to demonstrate 
//  all insertion methods on Linked List 
#include <bits/stdc++.h>
using namespace std;
  
// A linked list node 
class Node 
{ 
     public :
     int data; 
     Node *next; 
}; 
  
/* Given a reference (pointer to pointer)
to the head of a list and an int, inserts
a new node on the front of the list. */
void push(Node** head_ref, int new_data) 
{ 
     /* 1. allocate node */
     Node* new_node = new Node();
  
     /* 2. put in the data */
     new_node->data = new_data; 
  
     /* 3. Make next of new node as head */
     new_node->next = (*head_ref); 
  
     /* 4. move the head to point to the new node */
     (*head_ref) = new_node; 
} 
  
/* Given a node prev_node, insert a new node after the given 
prev_node */
void insertAfter(Node* prev_node, int new_data) 
{ 
     /*1. check if the given prev_node is NULL */
     if (prev_node == NULL) 
     { 
         cout<< "the given previous node cannot be NULL" ; 
         return ; 
     } 
  
     /* 2. allocate new node */
     Node* new_node = new Node();
  
     /* 3. put in the data */
     new_node->data = new_data; 
  
     /* 4. Make next of new node as next of prev_node */
     new_node->next = prev_node->next; 
  
     /* 5. move the next of prev_node as new_node */
     prev_node->next = new_node; 
} 
  
/* Given a reference (pointer to pointer) to the head 
of a list and an int, appends a new node at the end */
void append(Node** head_ref, int new_data) 
{ 
     /* 1. allocate node */
     Node* new_node = new Node();
  
     Node *last = *head_ref; /* used in step 5*/
  
     /* 2. put in the data */
     new_node->data = new_data; 
  
     /* 3. This new node is going to be 
     the last node, so make next of 
     it as NULL*/
     new_node->next = NULL; 
  
     /* 4. If the Linked List is empty, then make the new node as head */
     if (*head_ref == NULL) 
     { 
         *head_ref = new_node; 
         return ; 
     } 
  
     /* 5. Else traverse till the last node */
     while (last->next != NULL) 
         last = last->next; 
  
     /* 6. Change the next of last node */
     last->next = new_node; 
     return ; 
} 
  
// This function prints contents of
// linked list starting from head 
void printList(Node *node) 
{ 
     while (node != NULL) 
     { 
         cout<< " " <<node->data; 
         node = node->next; 
     } 
} 
  
/* Driver code*/
int main() 
{ 
     /* Start with the empty list */
     Node* head = NULL; 
      
     // Insert 6. So linked list becomes 6->NULL 
     append(&head, 6); 
      
     // Insert 7 at the beginning. 
     // So linked list becomes 7->6->NULL 
     push(&head, 7); 
      
     // Insert 1 at the beginning. 
     // So linked list becomes 1->7->6->NULL 
     push(&head, 1); 
      
     // Insert 4 at the end. So 
     // linked list becomes 1->7->6->4->NULL 
     append(&head, 4); 
      
     // Insert 8, after 7. So linked 
     // list becomes 1->7->8->6->4->NULL 
     insertAfter(head->next, 8); 
      
     cout<< "Created Linked list is: " ; 
     printList(head); 
      
     return 0; 
} 
  
  
// This code is contributed by rathbhupendra

C

// A complete working C program to demonstrate all insertion methods
// on Linked List
#include <stdio.h>
#include <stdlib.h>
  
// A linked list node
struct Node
{
   int data;
   struct Node *next;
};
  
/* Given a reference (pointer to pointer) to the head of a list and 
    an int, inserts a new node on the front of the list. */
void push( struct Node** head_ref, int new_data)
{
     /* 1. allocate node */
     struct Node* new_node = ( struct Node*) malloc ( sizeof ( struct Node));
  
     /* 2. put in the data  */
     new_node->data  = new_data;
  
     /* 3. Make next of new node as head */
     new_node->next = (*head_ref);
  
     /* 4. move the head to point to the new node */
     (*head_ref)    = new_node;
}
  
/* Given a node prev_node, insert a new node after the given 
    prev_node */
void insertAfter( struct Node* prev_node, int new_data)
{
     /*1. check if the given prev_node is NULL */
     if (prev_node == NULL)
     {
       printf ( "the given previous node cannot be NULL" );
       return ;
     }
  
     /* 2. allocate new node */
     struct Node* new_node =( struct Node*) malloc ( sizeof ( struct Node));
  
     /* 3. put in the data  */
     new_node->data  = new_data;
  
     /* 4. Make next of new node as next of prev_node */
     new_node->next = prev_node->next;
  
     /* 5. move the next of prev_node as new_node */
     prev_node->next = new_node;
}
  
/* Given a reference (pointer to pointer) to the head
    of a list and an int, appends a new node at the end  */
void append( struct Node** head_ref, int new_data)
{
     /* 1. allocate node */
     struct Node* new_node = ( struct Node*) malloc ( sizeof ( struct Node));
  
     struct Node *last = *head_ref;  /* used in step 5*/
  
     /* 2. put in the data  */
     new_node->data  = new_data;
  
     /* 3. This new node is going to be the last node, so make next of
           it as NULL*/
     new_node->next = NULL;
  
     /* 4. If the Linked List is empty, then make the new node as head */
     if (*head_ref == NULL)
     {
        *head_ref = new_node;
        return ;
     }
  
     /* 5. Else traverse till the last node */
     while (last->next != NULL)
         last = last->next;
  
     /* 6. Change the next of last node */
     last->next = new_node;
     return ;
}
  
// This function prints contents of linked list starting from head
void printList( struct Node *node)
{
   while (node != NULL)
   {
      printf ( " %d " , node->data);
      node = node->next;
   }
}
  
/* Driver program to test above functions*/
int main()
{
   /* Start with the empty list */
   struct Node* head = NULL;
  
   // Insert 6.  So linked list becomes 6->NULL
   append(&head, 6);
  
   // Insert 7 at the beginning. So linked list becomes 7->6->NULL
   push(&head, 7);
  
   // Insert 1 at the beginning. So linked list becomes 1->7->6->NULL
   push(&head, 1);
  
   // Insert 4 at the end. So linked list becomes 1->7->6->4->NULL
   append(&head, 4);
  
   // Insert 8, after 7. So linked list becomes 1->7->8->6->4->NULL
   insertAfter(head->next, 8);
  
   printf ( "\n Created Linked list is: " );
   printList(head);
  
   return 0;
}

Java

// A complete working Java program to demonstrate all insertion methods
// on linked list
class LinkedList
{
     Node head;  // head of list
  
     /* Linked list Node*/
     class Node
     {
         int data;
         Node next;
         Node( int d) {data = d; next = null ; }
     }
  
     /* 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;
     }
  
     /* Inserts a new node after the given prev_node. */
     public void insertAfter(Node prev_node, int new_data)
     {
         /* 1. Check if the given Node is null */
         if (prev_node == null )
         {
             System.out.println( "The given previous node cannot be null" );
             return ;
         }
  
         /* 2 & 3: Allocate the Node &
                   Put in the data*/
         Node new_node = new Node(new_data);
  
         /* 4. Make next of new Node as next of prev_node */
         new_node.next = prev_node.next;
  
         /* 5. make next of prev_node as new_node */
         prev_node.next = new_node;
     }
     
     /* Appends a new node at the end.  This method is 
        defined inside LinkedList class shown above */
     public void append( int new_data)
     {
         /* 1. Allocate the Node &
            2. Put in the data
            3. Set next as null */
         Node new_node = new Node(new_data);
  
         /* 4. If the Linked List is empty, then make the
               new node as head */
         if (head == null )
         {
             head = new Node(new_data);
             return ;
         }
  
         /* 4. This new node is going to be the last node, so
               make next of it as null */
         new_node.next = null ;
  
         /* 5. Else traverse till the last node */
         Node last = head; 
         while (last.next != null )
             last = last.next;
  
         /* 6. Change the next of last node */
         last.next = new_node;
         return ;
     }
  
     /* This function prints contents of linked list starting from
         the given node */
     public void printList()
     {
         Node tnode = head;
         while (tnode != null )
         {
             System.out.print(tnode.data+ " " );
             tnode = tnode.next;
         }
     }
  
     /* Driver program to test above functions. Ideally this function
        should be in a separate user class.  It is kept here to keep
        code compact */
     public static void main(String[] args)
     {
         /* Start with the empty list */
         LinkedList llist = new LinkedList();
  
         // Insert 6.  So linked list becomes 6->NUllist
         llist.append( 6 );
  
         // Insert 7 at the beginning. So linked list becomes
         // 7->6->NUllist
         llist.push( 7 );
  
         // Insert 1 at the beginning. So linked list becomes
         // 1->7->6->NUllist
         llist.push( 1 );
  
         // Insert 4 at the end. So linked list becomes
         // 1->7->6->4->NUllist
         llist.append( 4 );
  
         // Insert 8, after 7. So linked list becomes
         // 1->7->8->6->4->NUllist
         llist.insertAfter(llist.head.next, 8 );
  
         System.out.println( "\nCreated Linked list is: " );
         llist.printList();
     }
}
// This code is contributed by Rajat Mishra

python

# A complete working Python program to demonstrate all
# insertion methods of linked list
  
# Node class
class Node:
  
     # Function to initialise the node object
     def __init__( self , data):
         self .data = data  # Assign data
         self . next = None  # Initialize next as null
  
  
# Linked List class contains a Node object
class LinkedList:
  
     # Function to initialize head
     def __init__( self ):
         self .head = None
  
  
     # Functio to insert a new node at the beginning
     def push( self , new_data):
  
         # 1 & 2: Allocate the Node &
         #        Put in the data
         new_node = Node(new_data)
  
         # 3. Make next of new Node as head
         new_node. next = self .head
  
         # 4. Move the head to point to new Node
         self .head = new_node
  
  
     # This function is in LinkedList class. Inserts a
     # new node after the given prev_node. This method is
     # defined inside LinkedList class shown above */
     def insertAfter( self , prev_node, new_data):
  
         # 1. check if the given prev_node exists
         if prev_node is None :
             print "The given previous node must inLinkedList."
             return
  
         #  2. create new node &
         #      Put in the data
         new_node = Node(new_data)
  
         # 4. Make next of new Node as next of prev_node
         new_node. next = prev_node. next
  
         # 5. make next of prev_node as new_node
         prev_node. next = new_node
  
  
     # This function is defined in Linked List class
     # Appends a new node at the end.  This method is
     # defined inside LinkedList class shown above */
     def append( self , new_data):
  
         # 1. Create a new node
         # 2. Put in the data
         # 3. Set next as None
         new_node = Node(new_data)
  
         # 4. If the Linked List is empty, then make the
         #    new node as head
         if self .head is None :
             self .head = new_node
             return
  
         # 5. Else traverse till the last node
         last = self .head
         while (last. next ):
             last = last. next
  
         # 6. Change the next of last node
         last. next =  new_node
  
  
     # Utility function to print the linked list
     def printList( self ):
         temp = self .head
         while (temp):
             print temp.data, temp = temp. next
  
  
  
# Code execution starts here
if __name__ = = '__main__' :
  
     # Start with the empty list
     llist = LinkedList()
  
     # Insert 6.  So linked list becomes 6->None
     llist.append( 6 )
  
     # Insert 7 at the beginning. So linked list becomes 7->6->None
     llist.push( 7 );
  
     # Insert 1 at the beginning. So linked list becomes 1->7->6->None
     llist.push( 1 );
  
     # Insert 4 at the end. So linked list becomes 1->7->6->4->None
     llist.append( 4 )
  
     # Insert 8, after 7. So linked list becomes 1 -> 7-> 8-> 6-> 4-> None
     llist.insertAfter(llist.head. next , 8 )
  
     print 'Created linked list is:' , llist.printList()
  
# This code is contributed by Manikantan Narasimhan

C#

// A complete working C# program to demonstrate 
// all insertion methods on linked list
using System;
      
class GFG
{
     public Node head; // head of list
  
     /* Linked list Node*/
     public class Node
     {
         public int data;
         public Node next;
         public Node( int d) {data = d; next = null ;}
     }
  
     /* 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;
     }
  
     /* Inserts a new node after the given prev_node. */
     public void insertAfter(Node prev_node, int new_data)
     {
         /* 1. Check if the given Node is null */
         if (prev_node == null )
         {
             Console.WriteLine( "The given previous" + 
                               " node cannot be null" );
             return ;
         }
  
         /* 2 & 3: Allocate the Node &
                 Put in the data*/
         Node new_node = new Node(new_data);
  
         /* 4. Make next of new Node as
               next of prev_node */
         new_node.next = prev_node.next;
  
         /* 5. make next of prev_node as new_node */
         prev_node.next = new_node;
     }
      
     /* Appends a new node at the end. This method is 
     defined inside LinkedList class shown above */
     public void append( int new_data)
     {
         /* 1. Allocate the Node &
         2. Put in the data
         3. Set next as null */
         Node new_node = new Node(new_data);
  
         /* 4. If the Linked List is empty, then make the new node as head */
         if (head == null )
         {
             head = new Node(new_data);
             return ;
         }
  
         /* 4. This new node is going to be the last node, so make next of it as null */
         new_node.next = null ;
  
         /* 5. Else traverse till the last node */
         Node last = head; 
         while (last.next != null )
             last = last.next;
  
         /* 6. Change the next of last node */
         last.next = new_node;
         return ;
     }
  
     /* This function prints contents of linked list 
     starting from the given node */
     public void printList()
     {
         Node tnode = head;
         while (tnode != null )
         {
             Console.Write(tnode.data + " " );
             tnode = tnode.next;
         }
     }
  
     // Driver Code
     public static void Main(String[] args)
     {
         /* Start with the empty list */
         GFG llist = new GFG();
  
         // Insert 6. So linked list becomes 6->NUllist
         llist.append(6);
  
         // Insert 7 at the beginning. 
         // So linked list becomes 7->6->NUllist
         llist.push(7);
  
         // Insert 1 at the beginning. 
         // So linked list becomes 1->7->6->NUllist
         llist.push(1);
  
         // Insert 4 at the end. So linked list becomes
         // 1->7->6->4->NUllist
         llist.append(4);
  
         // Insert 8, after 7. So linked list becomes
         // 1->7->8->6->4->NUllist
         llist.insertAfter(llist.head.next, 8);
  
         Console.Write( "Created Linked list is: " );
         llist.printList();
     }
}
  
// This code is contributed by Rajput-Ji

输出如下:

Created Linked list is:  1  7  8  6  4

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