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Author: coderpheonix

dublylinkedlist.cpp

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+
+#include<iostream>
+using namespace std;
+
+// Creating structure
+struct Node {
+    int data;
+    Node* next;
+    Node* prev;  // New pointer for the previous node
+
+    Node(int value) {
+        data = value;
+        next = nullptr;
+        prev = nullptr;  // Initialize prev to nullptr
+    }
+};
+
+// Creating class
+class LinkedList {
+    Node* head;
+    Node* tail;  // Add a tail pointer for efficient operations at the end
+public:
+    LinkedList() {
+        head = nullptr;
+        tail = nullptr;
+    }
+    void append(int value);
+    void deleteBeginning();
+    void printList();
+    void deleteEnd();
+    void showMid();
+    void insertAtPosition(int value, int position);
+    void reverseList();
+};
+
+// Append function to add value at the end
+void LinkedList::append(int value) {
+    Node* newNode = new Node(value);
+    if (head == nullptr) {
+        head = newNode;
+        tail = newNode;  // Update tail when the first node is added
+        return;
+    }
+
+    tail->next = newNode;  // Link the new node after tail
+    newNode->prev = tail;  // Set the new node's prev pointer to the current tail
+    tail = newNode;  // Update tail to the new node
+}
+
+// Function to delete from the beginning
+void LinkedList::deleteBeginning() {
+    if (head == nullptr) {
+        cout << "The List Is Empty" << endl;
+        return;
+    }
+
+    Node* del = head;
+    head = head->next;
+
+    if (head != nullptr) {
+        head->prev = nullptr;  // Update the prev pointer of the new head
+    } else {
+        tail = nullptr;  // If the list is empty, reset the tail pointer
+    }
+
+    delete del;
+}
+
+// Function to delete from the end
+void LinkedList::deleteEnd() {
+    if (tail == nullptr) {
+        cout << "The List is empty" << endl;
+        return;
+    }
+
+    Node* del = tail;
+    tail = tail->prev;
+
+    if (tail != nullptr) {
+        tail->next = nullptr;  // Update the next pointer of the new tail
+    } else {
+        head = nullptr;  // If the list is empty, reset the head pointer
+    }
+
+    delete del;
+}
+
+// Function to calculate the midpoint
+void LinkedList::showMid() {
+    Node *slow = head, *fast = head;
+
+    if (head == nullptr) {
+        cout << "The List Is Empty" << endl;
+        return;
+    }
+
+    while (fast != nullptr && fast->next != nullptr) {
+        slow = slow->next;
+        fast = fast->next->next;
+    }
+    cout << "The middle element is: " << slow->data << endl;
+}
+
+// Function to print the list
+void LinkedList::printList() {
+    Node* temp = head;
+    while (temp != nullptr) {
+        cout << temp->data << " <-> ";
+        temp = temp->next;
+    }
+    cout << "nullptr" << endl;
+}
+
+// Function to insert a node at a specific position
+void LinkedList::insertAtPosition(int value, int position) {
+    Node* newNode = new Node(value);
+    if (position == 1) {
+        newNode->next = head;
+        if (head != nullptr) {
+            head->prev = newNode;
+        }
+        head = newNode;
+
+        if (tail == nullptr) {
+            tail = newNode;  // If the list was empty, update the tail
+        }
+        return;
+    }
+
+    Node* temp = head;
+    for (int i = 1; i < position - 1 && temp != nullptr; ++i) {
+        temp = temp->next;
+    }
+
+    if (temp == nullptr) {
+        cout << "Position out of bounds" << endl;
+        delete newNode;
+    } else {
+        newNode->next = temp->next;
+        newNode->prev = temp;
+
+        if (temp->next != nullptr) {
+            temp->next->prev = newNode;
+        } else {
+            tail = newNode;  // If inserting at the end, update the tail
+        }
+
+        temp->next = newNode;
+    }
+}
+
+// Function to reverse the list
+void LinkedList::reverseList() {
+    Node* current = head;
+    Node* temp = nullptr;
+
+    while (current != nullptr) {
+        temp = current->prev;
+        current->prev = current->next;
+        current->next = temp;
+        current = current->prev;  // Move to the next node in the original list
+    }
+
+    if (temp != nullptr) {
+        head = temp->prev;  // Update the head to the new first node
+    }
+}
+
+// Main function to test the linked list operations
+int main() {
+    LinkedList list; // Create an instance of the LinkedList class
+
+    // Append some values to the list
+    list.append(10);
+    list.append(20);
+    list.append(30);
+    list.append(40);
+    list.append(100);
+
+    // Printing the value before deletion
+    cout << "Before Deletion:" << endl;
+    list.printList();
+
+    // Delete from the beginning and print the list
+    cout << "After deletion from beginning:" << endl;
+    list.deleteBeginning();
+    list.printList();
+
+    // Delete from the end and print the list
+    cout << "After deletion from end:" << endl;
+    list.deleteEnd();
+    list.printList();
+
+    // Insert at a specific position and print the list
+    cout << "After inserting 25 at position 2:" << endl;
+    list.insertAtPosition(25, 2);
+    list.printList();
+
+    // Calculate the midpoint
+    list.showMid();
+
+    // Reverse the current value
+    cout << "Before reversed:" << endl;
+    list.printList();
+    cout << "After reversed:" << endl;
+    list.reverseList();
+    list.printList();
+
+    return 0;
+}