📅  最后修改于: 2020-10-15 05:28:32             🧑  作者: Mango
在此程序中,我们将创建一个双向链接列表,并从列表的开头删除一个节点。如果列表为空,则print消息“列表为空”。如果列表不为空,那么我们将使头部指向列表中的下一个节点;我们将删除第一个节点。
考虑上面的例子,new是列表的头。使头指向列表中的下一个节点。现在,节点1将成为列表的新头,从而删除节点new。
#Represent a node of doubly linked list
class Node:
def __init__(self,data):
self.data = data;
self.previous = None;
self.next = None;
class DeleteStart:
#Represent the head and tail of the doubly linked list
def __init__(self):
self.head = None;
self.tail = None;
#addNode() will add a node to the list
def addNode(self, data):
#Create a new node
newNode = Node(data);
#If list is empty
if(self.head == None):
#Both head and tail will point to newNode
self.head = self.tail = newNode;
#head's previous will point to None
self.head.previous = None;
#tail's next will point to None, as it is the last node of the list
self.tail.next = None;
else:
#newNode will be added after tail such that tail's next will point to newNode
self.tail.next = newNode;
#newNode's previous will point to tail
newNode.previous = self.tail;
#newNode will become new tail
self.tail = newNode;
#As it is last node, tail's next will point to None
self.tail.next = None;
#deleteFromStart() will delete a node from the beginning of the list
def deleteFromStart(self):
#Checks whether list is empty
if(self.head == None):
return;
else:
#Checks whether the list contains only one element
if(self.head != self.tail):
#head will point to next node in the list
self.head = self.head.next;
#Previous node to current head will be made None
self.head.previous = None;
#If the list contains only one element
#then, it will remove the node, and now both head and tail will point to None
else:
self.head = self.tail = None;
#display() will print out the nodes of the list
def display(self):
#Node current will point to head
current = self.head;
if(self.head == None):
print("List is empty");
return;
while(current != None):
#Prints each node by incrementing pointer.
print(current.data),
current = current.next;
print();
dList = DeleteStart();
#Add nodes to the list
dList.addNode(1);
dList.addNode(2);
dList.addNode(3);
dList.addNode(4);
dList.addNode(5);
#Printing original list
print("Original List: ");
dList.display();
while(dList.head != None):
dList.deleteFromStart();
#Printing updated list
print("Updated List: ");
dList.display();
输出:
Original List:
1 2 3 4 5
Updated List:
2 3 4 5
Updated List:
3 4 5
Updated List:
4 5
Updated List:
5
Updated List:
List is empty
#include
//Represent a node of the doubly linked list
struct node{
int data;
struct node *previous;
struct node *next;
};
//Represent the head and tail of the doubly linked list
struct node *head, *tail = NULL;
//addNode() will add a node to the list
void addNode(int data) {
//Create a new node
struct node *newNode = (struct node*)malloc(sizeof(struct node));
newNode->data = data;
//If list is empty
if(head == NULL) {
//Both head and tail will point to newNode
head = tail = newNode;
//head's previous will point to NULL
head->previous = NULL;
//tail's next will point to NULL, as it is the last node of the list
tail->next = NULL;
}
else {
//newNode will be added after tail such that tail's next will point to newNode
tail->next = newNode;
//newNode's previous will point to tail
newNode->previous = tail;
//newNode will become new tail
tail = newNode;
//As it is last node, tail's next will point to NULL
tail->next = NULL;
}
}
//deleteFromStart() will delete a node from the beginning of the list
void deleteFromStart() {
//Checks whether list is empty
if(head == NULL) {
return;
}
else {
//Checks whether the list contains only one element
if(head != tail) {
//head will point to next node in the list
head = head->next;
//Previous node to current head will be made NULL
head->previous = NULL;
}
//If the list contains only one element
//then, it will remove node and now both head and tail will point to NULL
else {
head = tail = NULL;
}
}
}
//display() will print out the nodes of the list
void display() {
//Node current will point to head
struct node *current = head;
if(head == NULL) {
printf("List is empty\n");
return;
}
while(current != NULL) {
//Prints each node by incrementing pointer.
printf("%d ",current->data);
current = current->next;
}
printf("\n");
}
int main()
{
//Add nodes to the list
addNode(1);
addNode(2);
addNode(3);
addNode(4);
addNode(5);
//Printing original list
printf("Original List: \n");
display();
while(head != NULL) {
deleteFromStart();
//Printing updated list
printf("Updated List: \n");
display();
}
return 0;
}
输出:
Original List:
1 2 3 4 5
Updated List:
2 3 4 5
Updated List:
3 4 5
Updated List:
4 5
Updated List:
5
Updated List:
List is empty
public class DeleteStart {
//Represent a node of the doubly linked list
class Node{
int data;
Node previous;
Node next;
public Node(int data) {
this.data = data;
}
}
//Represent the head and tail of the doubly linked list
Node head, tail = null;
//addNode() will add a node to the list
public void addNode(int data) {
//Create a new node
Node newNode = new Node(data);
//If list is empty
if(head == null) {
//Both head and tail will point to newNode
head = tail = newNode;
//head's previous will point to null
head.previous = null;
//tail's next will point to null, as it is the last node of the list
tail.next = null;
}
else {
//newNode will be added after tail such that tail's next will point to newNode
tail.next = newNode;
//newNode's previous will point to tail
newNode.previous = tail;
//newNode will become new tail
tail = newNode;
//As it is last node, tail's next will point to null
tail.next = null;
}
}
//deleteFromStart() will delete a node from the beginning of the list
public void deleteFromStart() {
//Checks whether list is empty
if(head == null) {
return;
}
else {
//Checks whether the list contains only one element
if(head != tail) {
//head will point to next node in the list
head = head.next;
//Previous node to current head will be made null
head.previous = null;
}
//If the list contains only one element
//then, it will remove node and now both head and tail will point to null
else {
head = tail = null;
}
}
}
//display() will print out the nodes of the list
public void display() {
//Node current will point to head
Node current = head;
if(head == null) {
System.out.println("List is empty");
return;
}
while(current != null) {
//Prints each node by incrementing the pointer.
System.out.print(current.data + " ");
current = current.next;
}
System.out.println();
}
public static void main(String[] args) {
DeleteStart dList = new DeleteStart();
//Add nodes to the list
dList.addNode(1);
dList.addNode(2);
dList.addNode(3);
dList.addNode(4);
dList.addNode(5);
//Printing original list
System.out.println("Original List: ");
dList.display();
while(dList.head != null) {
dList.deleteFromStart();
//Printing updated list
System.out.println("Updated List: ");
dList.display();
}
}
}
输出:
Original List:
1 2 3 4 5
Updated List:
2 3 4 5
Updated List:
3 4 5
Updated List:
4 5
Updated List:
5
Updated List:
List is empty
using System;
namespace DoublyLinkedList
{
public class Program
{
//Represent a node of the doubly linked list
public class Node{
public T data;
public Node previous;
public Node next;
public Node(T value) {
data = value;
}
}
public class DeleteStart{
//Represent the head and tail of the doubly linked list
public Node head = null;
public Node tail = null;
//addNode() will add a node to the list
public void addNode(T data) {
//Create a new node
Node newNode = new Node(data);
//If list is empty
if(head == null) {
//Both head and tail will point to newNode
head = tail = newNode;
//head's previous will point to null
head.previous = null;
//tail's next will point to null, as it is the last node of the list
tail.next = null;
}
else {
//newNode will be added after tail such that tail's next will point to newNode
tail.next = newNode;
//newNode's previous will point to tail
newNode.previous = tail;
//newNode will become new tail
tail = newNode;
//As it is last node, tail's next will point to null
tail.next = null;
}
}
//deleteFromStart() will delete a node from the beginning of the list
public void deleteFromStart() {
//Checks whether list is empty
if(head == null) {
return;
}
else {
//Checks whether the list contains only one element
if(head != tail) {
//head will point to next node in the list
head = head.next;
//Previous node to current head will be made null
head.previous = null;
}
//If the list contains only one element
//then, it will remove node and now both head and tail will point to null
else {
head = tail = null;
}
}
}
//display() will print out the nodes of the list
public void display() {
//Node current will point to head
Node current = head;
if(head == null) {
Console.WriteLine("List is empty");
return;
}
while(current != null) {
//Prints each node by incrementing the pointer.
Console.Write(current.data + " ");
current = current.next;
}
Console.WriteLine();
}
}
public static void Main()
{
DeleteStart dList = new DeleteStart();
//Add nodes to the list
dList.addNode(1);
dList.addNode(2);
dList.addNode(3);
dList.addNode(4);
dList.addNode(5);
//Printing original list
Console.WriteLine("Original List: ");
dList.display();
while(dList.head != null) {
dList.deleteFromStart();
//Printing updated list
Console.WriteLine("Updated List: ");
dList.display();
}
}
}
}
输出:
Original List:
1 2 3 4 5
Updated List:
2 3 4 5
Updated List:
3 4 5
Updated List:
4 5
Updated List:
5
Updated List:
List is empty
data = $data;
}
}
class DeleteStart{
//Represent the head and tail of the doubly linked list
public $head;
public $tail;
function __construct(){
$this->head = NULL;
$this->tail = NULL;
}
//addNode() will add a node to the list
function addNode($data) {
//Create a new node
$newNode = new Node($data);
//If list is empty
if($this->head == NULL) {
//Both head and tail will point to newNode
$this->head = $this->tail = $newNode;
//head's previous will point to NULL
$this->head->previous = NULL;
//tail's next will point to NULL, as it is the last node of the list
$this->tail->next = NULL;
}
else {
//newNode will be added after tail such that tail's next will point to newNode
$this->tail->next = $newNode;
//newNode's previous will point to tail
$newNode->previous = $this->tail;
//newNode will become new tail
$this->tail = $newNode;
//As it is last node, tail's next will point to NULL
$this->tail->next = NULL;
}
}
//deleteFromStart() will delete a node from the beginning of the list
function deleteFromStart() {
//Checks whether list is empty
if($this->head == NULL) {
return;
}
else {
//Checks whether the list contains only one element
if($this->head != $this->tail) {
//head will point to next node in the list
$this->head = $this->head->next;
//Previous node to current head will be made NULL
$this->head->previous = NULL;
}
//If the list contains only one element
//then, it will remove node and now both head and tail will point to NULL
else {
$this->head = $this->tail = NULL;
}
}
}
//display() will print out the nodes of the list
function display() {
//Node current will point to head
$current = $this->head;
if($this->head == NULL) {
print("List is empty
");
return;
}
while($current != NULL) {
//Prints each node by incrementing pointer.
print($current->data . " ");
$current = $current->next;
}
print("
");
}
}
$dList = new DeleteStart();
//Add nodes to the list
$dList->addNode(1);
$dList->addNode(2);
$dList->addNode(3);
$dList->addNode(4);
$dList->addNode(5);
//Printing original list
print("Original List:
");
$dList->display();
while($dList->head != NULL) {
$dList->deleteFromStart();
//Printing updated list
print("Updated List:
");
$dList->display();
}
?>
输出:
Original List:
1 2 3 4 5
Updated List:
2 3 4 5
Updated List:
3 4 5
Updated List:
4 5
Updated List:
5
Updated List:
List is empty