Merge pull request #219 from AyushAnand413/feature/menu-driven-linkedlist

Added MenuDrivenLinkedList.cpp implementation in C++

Author: Pradeepsingh61

CPP/data_structures/linked_lists/MenuDrivenLinkedList.cpp

@@ -0,0 +1,312 @@
+
+/*
+ * Algorithm: Menu Driven Linked List
+ * Description: Implementation of a linked list with menu options 
+ *              (insert, delete, display,middle, exit and many more ).
+ * Time Complexity: O(n) for insertion/search/deletion
+ * Space Complexity: O(n)
+ * Author: Ayush Kumar Anand
+ * Date: 2025-10-01
+ */
+#include <iostream>
+using namespace std;
+
+class LinkedList {
+private:
+    struct Node {
+        int data;
+        Node* next;
+    };
+    Node* head = nullptr;
+
+public:
+    // Display list
+    void display() {
+        if (!head) {
+            cout << "List is empty!\n";
+            return;
+        }
+        cout << "Linked List: ";
+        Node* temp = head;
+        while (temp) {
+            cout << temp->data << " -> ";
+            temp = temp->next;
+        }
+        cout << "NULL\n";
+    }
+
+    // Create list with n nodes
+    void createList(int n) {
+        head = nullptr;
+        Node *temp = nullptr;
+        for (int i = 0; i < n; i++) {
+            int val;
+            cout << "Enter value for node " << i + 1 << ": ";
+            cin >> val;
+            Node* newNode = new Node{val, nullptr};
+            if (!head) {
+                head = newNode;
+                temp = head;
+            } else {
+                temp->next = newNode;
+                temp = newNode;
+            }
+        }
+        cout << "List created successfully\n";
+    }
+
+    // Insert at beginning
+    void insertAtBeginning(int val) {
+        Node* newNode = new Node{val, head};
+        head = newNode;
+    }
+
+    // Insert at end
+    void insertAtEnd(int val) {
+        Node* newNode = new Node{val, nullptr};
+        if (!head) {
+            head = newNode;
+            return;
+        }
+        Node* temp = head;
+        while (temp->next) temp = temp->next;
+        temp->next = newNode;
+    }
+
+    // Insert at position
+    void insertAtPosition(int pos, int val) {
+        Node* newNode = new Node{val, nullptr};
+        if (pos == 1) {
+            newNode->next = head;
+            head = newNode;
+            return;
+        }
+        Node* temp = head;
+        for (int i = 1; temp && i < pos - 1; i++) temp = temp->next;
+        if (!temp) {
+            cout << "Position out of range!\n";
+            delete newNode;
+            return;
+        }
+        newNode->next = temp->next;
+        temp->next = newNode;
+    }
+
+    // Insert after element
+    void insertAfterElement(int element, int val) {
+        Node* temp = head;
+        while (temp && temp->data != element) temp = temp->next;
+        if (!temp) {
+            cout << "Element " << element << " not found!\n";
+            return;
+        }
+        Node* newNode = new Node{val, temp->next};
+        temp->next = newNode;
+        cout << "Inserted " << val << " after " << element << "\n";
+    }
+
+    // Delete first node
+    void deleteFirst() {
+        if (!head) {
+            cout << "List is empty!\n";
+            return;
+        }
+        Node* temp = head;
+        head = head->next;
+        cout << "Deleted node with value " << temp->data << "\n";
+        delete temp;
+    }
+
+    // Delete last node
+    void deleteLast() {
+        if (!head) {
+            cout << "List is empty!\n";
+            return;
+        }
+        if (!head->next) {
+            cout << "Deleted node with value " << head->data << "\n";
+            delete head;
+            head = nullptr;
+            return;
+        }
+        Node* temp = head;
+        while (temp->next->next) temp = temp->next;
+        cout << "Deleted node with value " << temp->next->data << "\n";
+        delete temp->next;
+        temp->next = nullptr;
+    }
+
+    // Delete at position
+    void deleteAtPosition(int pos) {
+        if (!head) {
+            cout << "List is empty!\n";
+            return;
+        }
+        Node* temp = head;
+        if (pos == 1) {
+            head = head->next;
+            cout << "Deleted node with value " << temp->data << " at position 1\n";
+            delete temp;
+            return;
+        }
+        for (int i = 1; temp && i < pos - 1; i++) temp = temp->next;
+        if (!temp || !temp->next) {
+            cout << "Wrong position!\n";
+            return;
+        }
+        Node* del = temp->next;
+        temp->next = del->next;
+        cout << "Deleted node with value " << del->data << " at position " << pos << "\n";
+        delete del;
+    }
+
+    // Delete after element
+    void deleteAfterElement(int element) {
+        Node* temp = head;
+        while (temp && temp->data != element) temp = temp->next;
+        if (!temp) {
+            cout << "Element " << element << " not found!\n";
+            return;
+        }
+        if (!temp->next) {
+            cout << "No node exists after element " << element << "\n";
+            return;
+        }
+        Node* del = temp->next;
+        temp->next = del->next;
+        cout << "Deleted node with value " << del->data << " after element " << element << "\n";
+        delete del;
+    }
+
+    // Append another list
+    void appendList() {
+        int n, val;
+        cout << "Enter number of nodes to append: ";
+        cin >> n;
+        if (n <= 0) {
+            cout << "Nothing to append!\n";
+            return;
+        }
+        Node* newHead = nullptr;
+        Node* temp = nullptr;
+        for (int i = 0; i < n; i++) {
+            cout << "Enter value for node " << i + 1 << ": ";
+            cin >> val;
+            Node* newNode = new Node{val, nullptr};
+            if (!newHead) {
+                newHead = newNode;
+                temp = newHead;
+            } else {
+                temp->next = newNode;
+                temp = newNode;
+            }
+        }
+        if (!head) {
+            head = newHead;
+            return;
+        }
+        temp = head;
+        while (temp->next) temp = temp->next;
+        temp->next = newHead;
+        cout << "Another list appended successfully!\n";
+    }
+
+    // Sort list
+    void sortList() {
+        if (!head) {
+            cout << "List is empty!\n";
+            return;
+        }
+        for (Node* i = head; i; i = i->next) {
+            for (Node* j = i->next; j; j = j->next) {
+                if (i->data > j->data) swap(i->data, j->data);
+            }
+        }
+        cout << "List sorted successfully!\n";
+    }
+
+    // Reverse print
+    void reversePrint(Node* node) {
+        if (!node) return;
+        reversePrint(node->next);
+        cout << node->data << " -> ";
+    }
+    void reverse() {
+        cout << "Reversed List: ";
+        reversePrint(head);
+        cout << "NULL\n";
+    }
+
+    // Display middle node
+    void displayMiddle() {
+        if (!head) {
+            cout << "List is empty!\n";
+            return;
+        }
+        Node* slow = head;
+        Node* fast = head;
+        while (fast && fast->next) {
+            slow = slow->next;
+            fast = fast->next->next;
+        }
+        cout << "Middle node value: " << slow->data << "\n";
+    }
+
+    // Count nodes
+    int countNodes() {
+        int count = 0;
+        for (Node* temp = head; temp; temp = temp->next) count++;
+        return count;
+    }
+
+    // Find largest and smallest
+    void findLargestSmallest() {
+        if (!head) {
+            cout << "List is empty!\n";
+            return;
+        }
+        int largest = head->data;
+        int smallest = head->data;
+        for (Node* temp = head; temp; temp = temp->next) {
+            if (temp->data > largest) largest = temp->data;
+            if (temp->data < smallest) smallest = temp->data;
+        }
+        cout << "Largest = " << largest << ", Smallest = " << smallest << "\n";
+    }
+};
+
+int main() {
+    LinkedList list;
+    int choice, n, val, pos, element;
+
+    while (true) {
+        cout << "\n--- Linked List Menu ---\n";
+        cout << "0. Display\n1. Create a single linked list\n2. Insert at beginning\n3. Insert at end\n";
+        cout << "4. Insert at ith position\n5. Insert after element\n6. Delete first node\n7. Delete last node\n";
+        cout << "8. Delete at ith position\n9. Delete after element\n11. Append another list\n12. Sort list\n";
+        cout << "13. Print reversed list\n14. Display middle node\n15. Count nodes\n16. Find largest & smallest\n18. EXIT\n";
+        cout << "Enter your choice: ";
+        cin >> choice;
+
+        switch (choice) {
+            case 0: list.display(); break;
+            case 1: cout << "Enter number of nodes: "; cin >> n; list.createList(n); break;
+            case 2: cout << "Enter value: "; cin >> val; list.insertAtBeginning(val); break;
+            case 3: cout << "Enter value: "; cin >> val; list.insertAtEnd(val); break;
+            case 4: cout << "Enter position and value: "; cin >> pos >> val; list.insertAtPosition(pos, val); break;
+            case 5: cout << "Enter element and value: "; cin >> element >> val; list.insertAfterElement(element, val); break;
+            case 6: list.deleteFirst(); break;
+            case 7: list.deleteLast(); break;
+            case 8: cout << "Enter position to delete: "; cin >> pos; list.deleteAtPosition(pos); break;
+            case 9: cout << "Enter element after which to delete: "; cin >> element; list.deleteAfterElement(element); break;
+            case 11: list.appendList(); break;
+            case 12: list.sortList(); break;
+            case 13: list.reverse(); break;
+            case 14: list.displayMiddle(); break;
+            case 15: cout << "Total nodes: " << list.countNodes() << "\n"; break;
+            case 16: list.findLargestSmallest(); break;
+            case 18: exit(0);
+            default: cout << "Invalid choice!\n"; break;
+        }
+    }
+}