Assignment-5

#include <iostream>
using namespace std;

class Node {
public:
    string route;
    Node *next;

    Node() {  // Default constructor
        route = "";
        next = NULL;
    }
    
    Node(string r) {  // Constructor with route data
        route = r;
        next = NULL;
    }
};

class CircularRouteList {
    Node *head;

public:
    CircularRouteList() {
        head = NULL;  // Initialize head to nullptr
    }

    // Function to add a new route
    void AddRoute(string r) {
        Node *nn = new Node(r);
        if (head == NULL) {
            head = nn;
            nn->next = head;  // Point to itself (circular)
        } else {
            nn->next = head;
            Node *temp = head;
            while (temp->next != head) {
                temp = temp->next;  // Traverse to last node
            }
            temp->next = nn;  // Link new node
        }
    }

    // Function to remove a route at a given position
    void RemoveRoute(int pos) {
        if (head == NULL) {
            cout << "No routes to remove." << endl;
            return;
        }

        Node *temp = head;

        // Deleting the first route (head)
        if (pos == 1) {
            if (head->next == head) {  // Only one node in the list
                delete head;
                head = NULL;
            } else {
                // Find the last node
                while (temp->next != head) {
                    temp = temp->next;
                }
                // Update links
                temp->next = head->next;  // Bypass the head node
                delete head;  // Delete the old head
                head = temp->next;  // Update head to next node
            }
            return;
        }

        // Deleting a node at a given position
        int currpos = 1;
        while (currpos < pos - 1 && temp->next != head) {
            temp = temp->next;
            currpos++;
        }

        // Check if the position is valid
        if (currpos == pos - 1 && temp->next != head) {
            Node *toDelete = temp->next;  // Node to be deleted
            temp->next = toDelete->next;  // Bypass the node
            delete toDelete;  // Delete the node
        } else {
            cout << "Position out of bounds." << endl;
        }
    }

    // Function to display all the routes
    void DisplayRoutes() {
        if (head == NULL) {
            cout << "\nNo routes available.";
            return;
        }
        
        Node *temp = head;
        cout << "Routes: ";
        do {
            cout << temp->route << " -> ";
            temp = temp->next;  // Move to next node
        } while (temp != head);  // Stop when back to head
        cout << "(back to start)" << endl;
    }
};

// Menu-driven program to simulate the delivery service navigation system
int main() {
    CircularRouteList routeList;
    int choice;
    string routeName;
    int pos;

    do {
        cout << "\n--- Delivery Service Navigation System ---";
        cout << "\n1. Add route";
        cout << "\n2. Remove route";
        cout << "\n3. Display routes";
        cout << "\n4. Exit";
        cout << "\nEnter your choice: ";
        cin >> choice;

        switch (choice) {
            case 1:
                cout << "Enter the route name to add: ";
                cin >> routeName;
                routeList.AddRoute(routeName);
                break;

            case 2:
                cout << "Enter the position of the route to remove: ";
                cin >> pos;
                routeList.RemoveRoute(pos);
                break;

            case 3:
                routeList.DisplayRoutes();
                break;

            case 4:
                cout << "Exiting navigation system..." << endl;
                break;

            default:
                cout << "Invalid choice. Please try again." << endl;
        }
    } while (choice != 4);

    return 0;
}