现在您已经了解了链表及其类型的基本概念,是时候深入了解可以执行的常见操作了。
请记住两个要点:
- 头指向链接列表的第一个节点
- 最后一个节点的next指针为NULL ,因此,如果下一个当前节点为NULL ,则我们到达链表的末尾。
在所有示例中,我们将假定链表具有三个节点1 --->2 --->3
,其节点结构如下:
struct node
{
int data;
struct node *next;
};
如何遍历链接列表
显示链接列表的内容非常简单。我们继续将临时节点移至下一个节点并显示其内容。
当temp为NULL时 ,我们知道我们已经到达链表的末尾,因此我们退出了while循环。
struct node *temp = head;
printf("\n\nList elements are - \n");
while(temp != NULL)
{
printf("%d --->",temp->data);
temp = temp->next;
}
该程序的输出为:
List elements are -
1 --->2 --->3 --->
如何将元素添加到链接列表
您可以将元素添加到链接列表的开始,中间或结尾。
添加到开头
- 为新节点分配内存
- 存储数据
- 更改新节点的下一个指向头
- 将头更改为指向最近创建的节点
struct node *newNode;
newNode = malloc(sizeof(struct node));
newNode->data = 4;
newNode->next = head;
head = newNode;
添加到最后
- 为新节点分配内存
- 存储数据
- 遍历到最后一个节点
- 将最后一个节点的下一个更改为最近创建的节点
struct node *newNode;
newNode = malloc(sizeof(struct node));
newNode->data = 4;
newNode->next = NULL;
struct node *temp = head;
while(temp->next != NULL){
temp = temp->next;
}
temp->next = newNode;
添加到中间
- 分配内存并存储新节点的数据
- 在新节点的所需位置之前遍历到节点
- 更改下一个指针以在其间包括新节点
struct node *newNode;
newNode = malloc(sizeof(struct node));
newNode->data = 4;
struct node *temp = head;
for(int i=2; i < position; i++) {
if(temp->next != NULL) {
temp = temp->next;
}
}
newNode->next = temp->next;
temp->next = newNode;
如何从链接列表中删除
您可以从开头,结尾或特定位置删除。
从头删除
- 将头指向第二个节点
head = head->next;
从结尾删除
- 遍历到倒数第二个元素
- 将其下一个指针更改为null
struct node* temp = head;
while(temp->next->next!=NULL){
temp = temp->next;
}
temp->next = NULL;
从中间删除
- 在要删除的元素之前遍历到元素
- 更改下一个指针以将节点从链中排除
for(int i=2; i< position; i++) {
if(temp->next!=NULL) {
temp = temp->next;
}
}
temp->next = temp->next->next;
在Python,Java,C和C++中实现LinkedList操作
Python
爪哇
C
C++
# Linked list operations in Python
# Create a node
class Node:
def __init__(self, item):
self.item = item
self.next = None
class LinkedList:
def __init__(self):
self.head = None
# Insert at the beginning
def insertAtBeginning(self, data):
new_node = Node(data)
new_node.next = self.head
self.head = new_node
# Insert after a node
def insertAfter(self, node, data):
if node is None:
print("The given previous node must inLinkedList.")
return
new_node = Node(data)
new_node.next = node.next
node.next = new_node
# Insert at the end
def insertAtEnd(self, data):
new_node = Node(data)
if self.head is None:
self.head = new_node
return
last = self.head
while (last.next):
last = last.next
last.next = new_node
# Deleting a node
def deleteNode(self, position):
if self.head == None:
return
temp_node = self.head
if position == 0:
self.head = temp_node.next
temp_node = None
return
# Find the key to be deleted
for i in range(position - 1):
temp_node = temp_node.next
if temp_node is None:
break
# If the key is not present
if temp_node is None:
return
if temp_node.next is None:
return
next = temp_node.next.next
temp_node.next = None
temp_node.next = next
def printList(self):
temp_node = self.head
while (temp_node):
print(str(temp_node.item) + " ", end="")
temp_node = temp_node.next
if __name__ == '__main__':
llist = LinkedList()
llist.insertAtEnd(1)
llist.insertAtBeginning(2)
llist.insertAtBeginning(3)
llist.insertAtEnd(4)
llist.insertAfter(llist.head.next, 5)
print('Linked list:')
llist.printList()
print("\nAfter deleting an element:")
llist.deleteNode(3)
llist.printList()
// Linked list operations in Java
class LinkedList {
Node head;
// Create a node
class Node {
int item;
Node next;
Node(int d) {
item = d;
next = null;
}
}
public void insertAtBeginning(int data) {
// insert the item
Node new_node = new Node(data);
new_node.next = head;
head = new_node;
}
public void insertAfter(Node prev_node, int data) {
if (prev_node == null) {
System.out.println("The given previous node cannot be null");
return;
}
Node new_node = new Node(data);
new_node.next = prev_node.next;
prev_node.next = new_node;
}
public void insertAtEnd(int data) {
Node new_node = new Node(data);
if (head == null) {
head = new Node(data);
return;
}
new_node.next = null;
Node last = head;
while (last.next != null)
last = last.next;
last.next = new_node;
return;
}
void deleteNode(int position) {
if (head == null)
return;
Node node = head;
if (position == 0) {
head = node.next;
return;
}
// Find the key to be deleted
for (int i = 0; node != null && i < position - 1; i++)
node = node.next;
// If the key is not present
if (node == null || node.next == null)
return;
// Remove the node
Node next = node.next.next;
node.next = next;
}
public void printList() {
Node node = head;
while (node != null) {
System.out.print(node.item + " ");
node = node.next;
}
}
public static void main(String[] args) {
LinkedList llist = new LinkedList();
llist.insertAtEnd(1);
llist.insertAtBeginning(2);
llist.insertAtBeginning(3);
llist.insertAtEnd(4);
llist.insertAfter(llist.head.next, 5);
System.out.println("Linked list: ");
llist.printList();
System.out.println("\nAfter deleting an element: ");
llist.deleteNode(3);
llist.printList();
}
}
// Linked list operations in C
#include
#include
// Create a node
struct Node {
int item;
struct Node* next;
};
void insertAtBeginning(struct Node** ref, int data) {
// Allocate memory to a node
struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
// insert the item
new_node->item = data;
new_node->next = (*ref);
// Move head to new node
(*ref) = new_node;
}
// Insert a node after a node
void insertAfter(struct Node* node, int data) {
if (node == NULL) {
printf("the given previous node cannot be NULL");
return;
}
struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
new_node->item = data;
new_node->next = node->next;
node->next = new_node;
}
void insertAtEnd(struct Node** ref, int data) {
struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
struct Node* last = *ref;
new_node->item = data;
new_node->next = NULL;
if (*ref == NULL) {
*ref = new_node;
return;
}
while (last->next != NULL)
last = last->next;
last->next = new_node;
return;
}
void deleteNode(struct Node** ref, int key) {
struct Node *temp = *ref, *prev;
if (temp != NULL && temp->item == key) {
*ref = temp->next;
free(temp);
return;
}
// Find the key to be deleted
while (temp != NULL && temp->item != key) {
prev = temp;
temp = temp->next;
}
// If the key is not present
if (temp == NULL) return;
// Remove the node
prev->next = temp->next;
free(temp);
}
// Print the linked list
void printList(struct Node* node) {
while (node != NULL) {
printf(" %d ", node->item);
node = node->next;
}
}
// Driver program
int main() {
struct Node* head = NULL;
insertAtEnd(&head, 1);
insertAtBeginning(&head, 2);
insertAtBeginning(&head, 3);
insertAtEnd(&head, 4);
insertAfter(head->next, 5);
printf("Linked list: ");
printList(head);
printf("\nAfter deleting an element: ");
deleteNode(&head, 3);
printList(head);
}
// Linked list operations in C++
#include
#include
using namespace std;
// Create a node
struct Node {
int item;
struct Node* next;
};
void insertAtBeginning(struct Node** ref, int data) {
// Allocate memory to a node
struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
// insert the item
new_node->item = data;
new_node->next = (*ref);
// Move head to new node
(*ref) = new_node;
}
// Insert a node after a node
void insertAfter(struct Node* prev_node, int data) {
if (prev_node == NULL) {
cout << "the given previous node cannot be NULL";
return;
}
struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
new_node->item = data;
new_node->next = prev_node->next;
prev_node->next = new_node;
}
void insertAtEnd(struct Node** ref, int data) {
struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
struct Node* last = *ref;
new_node->item = data;
new_node->next = NULL;
if (*ref == NULL) {
*ref = new_node;
return;
}
while (last->next != NULL)
last = last->next;
last->next = new_node;
return;
}
void deleteNode(struct Node** ref, int key) {
struct Node *temp = *ref, *prev;
if (temp != NULL && temp->item == key) {
*ref = temp->next;
free(temp);
return;
}
// Find the key to be deleted
while (temp != NULL && temp->item != key) {
prev = temp;
temp = temp->next;
}
// If the key is not present
if (temp == NULL) return;
// Remove the node
prev->next = temp->next;
free(temp);
}
// Print the linked list
void printList(struct Node* node) {
while (node != NULL) {
cout << node->item << " ";
node = node->next;
}
}
// Driver program
int main() {
struct Node* head = NULL;
insertAtEnd(&head, 1);
insertAtBeginning(&head, 2);
insertAtBeginning(&head, 3);
insertAtEnd(&head, 4);
insertAfter(head->next, 5);
cout << "Linked list: ";
printList(head);
cout << "\nAfter deleting an element: ";
deleteNode(&head, 3);
printList(head);
}