search
HomeBackend DevelopmentC++Reverse a doubly linked list using C++

Reverse a doubly linked list using C++

Aug 30, 2023 pm 11:41 PM
c languageReverse linked listDoubly linked list

Reverse a doubly linked list using C++

In this article, we have a doubly linked list and we will explain the different ways to reverse a doubly linked list in C. For example -

Input : {1, 2, 3, 4}
Output : {4, 3, 2, 1}

Usually one method comes to mind, but we will use two methods - the normal method and the unorthodox method.

Normal Method

In this method we will go through the list and as we go through it we reverse it.

Example

#include <bits/stdc++.h>

using namespace std;

class Node {
   public:
   int data;
   Node *next;
   Node *prev;
};

void reverse(Node **head_ref) {
   auto temp = (*head_ref) -> next;
   (*head_ref) -> next = (*head_ref) -> prev;
   (*head_ref) -> prev = temp;
   if(temp != NULL) {
      (*head_ref) = (*head_ref) -> prev;
      reverse(head_ref);
   }
   else
      return;
}
void push(Node** head_ref, int new_data) {
   Node* new_node = new Node();
   new_node->data = new_data;

   new_node->prev = NULL;

   new_node->next = (*head_ref);
   if((*head_ref) != NULL)
      (*head_ref) -> prev = new_node ;

   (*head_ref) = new_node;
}
int main() {
   Node* head = NULL;
   push(&head, 6);
   push(&head, 4);
   push(&head, 8);
   push(&head, 9);
   auto node = head;
   cout << "Before\n" ;
   while(node != NULL) {
      cout << node->data << " ";
      node = node->next;
   }
   cout << "\n";
   reverse(&head);
   node = head;
   cout << "After\n";
   while(node != NULL) {
      cout << node->data << " ";
   node = node->next;
   }
   return 0;
}

Output

Before
9 8 4 6
After
6 4 8 9

This method requires O(N) time complexity, which is very good because of this complexity degree can be performed under higher constraints.

Unorthodox Method

As the name suggests, this is not a very common method that users think of, but we will explore this method as well. In this approach we will create a stack and keep pushing data into it and on pop we will change its value.

Example

#include <bits/stdc++.h>

using namespace std;

class Node {
   public:
   int data;
   Node *next;
   Node *prev;
};
void push(Node** head_ref, int new_data) {
   Node* new_node = new Node();
   new_node->data = new_data;

   new_node->prev = NULL;

   new_node->next = (*head_ref);
   if((*head_ref) != NULL)
      (*head_ref) -> prev = new_node ;

   (*head_ref) = new_node;
}
int main() {
   Node* head = NULL;
   push(&head, 6);
   push(&head, 4);
   push(&head, 8);
   push(&head, 9);
   auto node = head;
   cout >> "Before\n" ;
   while(node != NULL) {
      cout >> node->data >> " ";
      node = node->next;
   }
   cout >> "\n";
   stack<Node*> s;
   node = head;
   while(node) {
      head = node;
      s.push(node);
      node = node -> next;
   }
   while(!s.empty()) {
      auto x = s.top();
      auto temp = x -> prev;
      x -> prev = x -> next;
      x -> next = temp;
      s.pop();
   }
   node = head;
   cout << "After\n";
   while(node != NULL) {
      cout << node->data << " ";
   node = node->next;
   }
   return 0;
}

Output

Before
9 8 4 6
After
6 4 8 9

Explanation of the above code

In this approach we use a stack which is populated while traversing the list , then pop the items off the stack and change their values ​​so that the list is reversed. O(N) is the time complexity of this program, which also applies to higher constraints.

Conclusion

In this article, we solved a problem using or to reverse a doubly linked list without a stack. The time complexity is O(N), where N is the size of the list. We also learned a C program to solve this problem and complete methods (normal and unorthodox) to solve this problem. We can write the same program in other languages ​​such as C, java, python and other languages. We hope this article was helpful to you.

The above is the detailed content of Reverse a doubly linked list using C++. For more information, please follow other related articles on the PHP Chinese website!

Statement
This article is reproduced at:tutorialspoint. If there is any infringement, please contact admin@php.cn delete
The Future of C  : Adaptations and InnovationsThe Future of C : Adaptations and InnovationsApr 27, 2025 am 12:25 AM

The future of C will focus on parallel computing, security, modularization and AI/machine learning: 1) Parallel computing will be enhanced through features such as coroutines; 2) Security will be improved through stricter type checking and memory management mechanisms; 3) Modulation will simplify code organization and compilation; 4) AI and machine learning will prompt C to adapt to new needs, such as numerical computing and GPU programming support.

The Longevity of C  : Examining Its Current StatusThe Longevity of C : Examining Its Current StatusApr 26, 2025 am 12:02 AM

C is still important in modern programming because of its efficient, flexible and powerful nature. 1)C supports object-oriented programming, suitable for system programming, game development and embedded systems. 2) Polymorphism is the highlight of C, allowing the call to derived class methods through base class pointers or references to enhance the flexibility and scalability of the code.

C# vs. C   Performance: Benchmarking and ConsiderationsC# vs. C Performance: Benchmarking and ConsiderationsApr 25, 2025 am 12:25 AM

The performance differences between C# and C are mainly reflected in execution speed and resource management: 1) C usually performs better in numerical calculations and string operations because it is closer to hardware and has no additional overhead such as garbage collection; 2) C# is more concise in multi-threaded programming, but its performance is slightly inferior to C; 3) Which language to choose should be determined based on project requirements and team technology stack.

C  : Is It Dying or Simply Evolving?C : Is It Dying or Simply Evolving?Apr 24, 2025 am 12:13 AM

C isnotdying;it'sevolving.1)C remainsrelevantduetoitsversatilityandefficiencyinperformance-criticalapplications.2)Thelanguageiscontinuouslyupdated,withC 20introducingfeatureslikemodulesandcoroutinestoimproveusabilityandperformance.3)Despitechallen

C   in the Modern World: Applications and IndustriesC in the Modern World: Applications and IndustriesApr 23, 2025 am 12:10 AM

C is widely used and important in the modern world. 1) In game development, C is widely used for its high performance and polymorphism, such as UnrealEngine and Unity. 2) In financial trading systems, C's low latency and high throughput make it the first choice, suitable for high-frequency trading and real-time data analysis.

C   XML Libraries: Comparing and Contrasting OptionsC XML Libraries: Comparing and Contrasting OptionsApr 22, 2025 am 12:05 AM

There are four commonly used XML libraries in C: TinyXML-2, PugiXML, Xerces-C, and RapidXML. 1.TinyXML-2 is suitable for environments with limited resources, lightweight but limited functions. 2. PugiXML is fast and supports XPath query, suitable for complex XML structures. 3.Xerces-C is powerful, supports DOM and SAX resolution, and is suitable for complex processing. 4. RapidXML focuses on performance and parses extremely fast, but does not support XPath queries.

C   and XML: Exploring the Relationship and SupportC and XML: Exploring the Relationship and SupportApr 21, 2025 am 12:02 AM

C interacts with XML through third-party libraries (such as TinyXML, Pugixml, Xerces-C). 1) Use the library to parse XML files and convert them into C-processable data structures. 2) When generating XML, convert the C data structure to XML format. 3) In practical applications, XML is often used for configuration files and data exchange to improve development efficiency.

C# vs. C  : Understanding the Key Differences and SimilaritiesC# vs. C : Understanding the Key Differences and SimilaritiesApr 20, 2025 am 12:03 AM

The main differences between C# and C are syntax, performance and application scenarios. 1) The C# syntax is more concise, supports garbage collection, and is suitable for .NET framework development. 2) C has higher performance and requires manual memory management, which is often used in system programming and game development.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

SublimeText3 English version

SublimeText3 English version

Recommended: Win version, supports code prompts!

SecLists

SecLists

SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool