Data-Structures/Implement Adjacency List.cpp at master · Pooshan/Data-Structures · GitHub

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/*
 * C++ Program to Implement Adjacency List
 */
#include <iostream>
#include <cstdlib>
using namespace std;

/*
 * Adjacency List Node
 */
struct AdjListNode
{
    int dest;
    struct AdjListNode* next;
};

/*
 * Adjacency List
 */
struct AdjList
{
    struct AdjListNode *head;
};

/*
 * Class Graph
 */
class Graph
{
    private:
        int V;
        struct AdjList* array;
    public:
        Graph(int V)
        {
            this->V = V;
            array = new AdjList [V];
            for (int i = 0; i < V; ++i)
                array[i].head = NULL;
        }
        /*
         * Creating New Adjacency List Node
         */
        AdjListNode* newAdjListNode(int dest)
        {
            AdjListNode* newNode = new AdjListNode;
            newNode->dest = dest;
            newNode->next = NULL;
            return newNode;
        }
        /*
         * Adding Edge to Graph
         */
        void addEdge(int src, int dest)
        {
            AdjListNode* newNode = newAdjListNode(dest);
            newNode->next = array[src].head;
            array[src].head = newNode;
            newNode = newAdjListNode(src);
            newNode->next = array[dest].head;
            array[dest].head = newNode;
        }
        /*
         * Print the graph
         */
        void printGraph()
        {
            int v;
            for (v = 0; v < V; ++v)
            {
                AdjListNode* pCrawl = array[v].head;
                cout<<"\n Adjacency list of vertex "<<v<<"\n head ";
                while (pCrawl)
                {
                    cout<<"-> "<<pCrawl->dest;
                    pCrawl = pCrawl->next;
                }
                cout<<endl;
            }
        }
};

/*
 * Main
 */
int main()
{
    Graph gh(5);
    gh.addEdge(0, 1);
    gh.addEdge(0, 4);
    gh.addEdge(1, 2);
    gh.addEdge(1, 3);
    gh.addEdge(1, 4);
    gh.addEdge(2, 3);
    gh.addEdge(3, 4);

    // print the adjacency list representation of the above graph
    gh.printGraph();

    return 0;
}