Co je propojený seznam?

Propojený seznam je lineární datová struktura, která se skládá ze sekvence uzlů, kde každý uzel ukládá část dat a odkaz (ukazatel) na další uzel v seznamu. Propojené seznamy jsou užitečné pro ukládání kolekcí dat, když velikost kolekce není známa předem nebo když jsou data často vkládána nebo mazána.

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V C++ můžeme vytvořit propojený seznam definováním třídy uzlů a třídy propojeného seznamu. Třída uzlu bude představovat jeden uzel v seznamu a bude obsahovat datové pole a ukazatel na další uzel. Třída propojeného seznamu bude obsahovat hlavní ukazatel na první uzel v seznamu a různé metody pro vkládání, mazání a procházení uzlů v seznamu.

Zde je příklad třídy uzlů v C++:

 class Node { public: int data; Node *next; Node(int data) { this->data = data; this->next = nullptr; } }; 

Tato třída uzlů má data veřejného datového pole typu int a veřejný ukazatel vedle dalšího uzlu v seznamu. Má také konstruktor, který inicializuje datové pole a nastaví další ukazatel na nullptr.

Zde je příklad, jak používat třídy uzlu a propojených seznamů k vytvoření a manipulaci s propojeným seznamem v C++:

 #include using namespace std; // Node class class Node { public: int data; Node *next; Node(int data) { this-&gt;data = data; this-&gt;next = nullptr; } }; // Linked list class class LinkedList { private: Node *head; public: LinkedList() { this-&gt;head = nullptr; } void insertAtBeginning(int data) { Node *newNode = new Node(data); newNode-&gt;next = head; head = newNode; } void insertAtEnd(int data) { Node *newNode = new Node(data); if (head == nullptr) { head = newNode; return; } Node *temp = head; while (temp-&gt;next != nullptr) { temp = temp-&gt;next; } temp-&gt;next = newNode; } void deleteAtBeginning() { if (head == nullptr) { return; } Node *temp = head; head = head-&gt;next; delete temp; } void deleteAtEnd() { if (head == nullptr) { return; } if (head-&gt;next == nullptr) { delete head; head = nullptr; return; } Node *temp = head; while (temp-&gt;next-&gt;next != nullptr) { temp = temp-&gt;next; } delete temp-&gt;next; temp-&gt;next = nullptr; } void printList() { Node *temp = head; while (temp != nullptr) { cout <data <next; } cout << endl; }; int main() { create a linked list linkedlist list; insert some nodes at the beginning of list.insertatbeginning(3); list.insertatbeginning(2); list.insertatbeginning(1); end list.insertatend(4); list.insertatend(5); list.insertatend(6); print 'original list: '; list.printlist(); delete node list.deleteatbeginning(); again 'list after deleting beginning: list.deleteatend(); end: return 0; < pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/94/create-linked-list-c.webp" alt="Create Linked List In C++"> <p> <strong>Explanation:</strong> </p> <p>This linked list class has a private field head that points to the first node in the List and various public methods for inserting and deleting nodes at the beginning and end of the List and for printing the List to the console. This program will create a linked list, insert some nodes at the beginning and end of the List, delete a node at the beginning and end of the List, and print the List to the console.</p> <p> <strong>Here is an example of how to create a linked list in C++ using a template class:</strong> </p> <pre> #include template class Node { public: T data; Node *next; Node(T data) { this-&gt;data = data; this-&gt;next = nullptr; } }; template class LinkedList { private: Node *head; public: LinkedList() { this-&gt;head = nullptr; } void insertAtBeginning(T data) { Node *newNode = new Node(data); newNode-&gt;next = head; head = newNode; } void insertAtEnd(T data) { Node *newNode = new Node(data); if (head == nullptr) { head = newNode; return; } Node *temp = head; while (temp-&gt;next != nullptr) { temp = temp-&gt;next; } temp-&gt;next = newNode; } void deleteAtBeginning() { if (head == nullptr) { return; } Node *temp = head; head = head-&gt;next; delete temp; } void deleteAtEnd() { if (head == nullptr) { return; } if (head-&gt;next == nullptr) { delete head; head = nullptr; return; } Node *temp = head; while (temp-&gt;next-&gt;next != nullptr) { temp = temp-&gt;next; } delete temp-&gt;next; temp-&gt;next = nullptr; } void printList() { Node *temp = head; while (temp != nullptr) { std::cout <data <next; } std::cout << std::endl; }; int main() { create a linked list linkedlist list; insert some nodes at the beginning of list.insertatbeginning(3); list.insertatbeginning(2); list.insertatbeginning(1); end list.insertatend(4); list.insertatend(5); list.insertatend(6); print 'original list: '; list.printlist(); delete node list.deleteatbeginning(); again 'list after deleting beginning: list.deleteatend(); end: return 0; < pre> <p> <strong>Output:</strong> </p> <img src="//techcodeview.com/img/c-tutorial/94/create-linked-list-c-2.webp" alt="Create Linked List In C++"> <p> <strong>Explanation:</strong> </p> <p>In the above code, we have defined a template class Node that represents a single node in a linked list. The Node class has a public data field data of type T (where T is a template parameter) and a public pointer next to the next node in the List. It also has a constructor that initializes the data field and sets the next pointer to nullptr.</p> <p>We have also defined a template class, LinkedList, that represents a linked list and contains a private field head that points to the first node in the List. The LinkedList class has various public methods for inserting and deleting nodes at the beginning and end of the List and for printing the List to the console.</p> <p>The insertAtBeginning method creates a new node with the given data and inserts it at the beginning of the List by updating the head pointer. The insertAtEnd method creates a new node with the given data and inserts it at the end of the List by traversing it and updating the last node&apos;s next pointer. The deleteAtBeginning method deletes the first node in the List by updating the head pointer and freeing up the memory used by the node. The deleteAtEnd method deletes the last node in the List by traversing the List and updating the next pointer of the second to the last node. The printList method traverses the List and prints the data of each node to the console.</p> <p>In the main function, we create an instance of the LinkedList class and call the various methods to insert and delete nodes and print the List. The output shows the original List, the List after deleting a node at the beginning, and the List after deleting a node at the end.</p> <hr></data></pre></data>