adjlist.cpp

#include <iostream>
using namespace std;

class Node {
public:
    int vertex;
    Node* next;

    Node(int v) {
        vertex = v;
        next = nullptr;
    }

    ~Node() {
        cout << "Deleted node with vertex " << vertex << endl;
    }
};

class Graph {
    int V;
    Node** adjList; // Array of linked lists

public:
    Graph(int vertices) {
        V = vertices;
        adjList = new Node*[V];

        for (int i = 0; i < V; i++)
            adjList[i] = nullptr; // Initialize list heads as NULL
    }

    void addEdge(int u, int v) {
        Node* newNode = new Node(v);
        newNode->next = adjList[u];
        adjList[u] = newNode;

        newNode = new Node(u); // Add edge for undirected graph
        newNode->next = adjList[v];
        adjList[v] = newNode;
    }

    void displayGraph() {
        for (int i = 0; i < V; i++) {
            cout << "Adjacency list of vertex " << i << ": ";
            Node* temp = adjList[i];
            while (temp) {
                cout << temp->vertex << " ";
                temp = temp->next;
            }
            cout << endl;
        }
    }

    ~Graph() {
        for (int i = 0; i < V; i++) {
            Node* temp = adjList[i];
            while (temp) {
                Node* nextNode = temp->next;
                delete temp;
                temp = nextNode;
            }
        }
        delete[] adjList;
        cout << "Graph deleted\n";
    }
};

int main() {
    int V, E;
    cout << "Enter number of vertices and edges: ";
    cin >> V >> E;

    Graph graph(V);

    cout << "Enter edges (u v):\n";
    for (int i = 0; i < E; i++) {
        int u, v;
        cin >> u >> v;
        graph.addEdge(u, v);
    }

    graph.displayGraph();

    return 0;
}