Question

how do I create a graph class to store a adjacency list representation of a graph? I need some help and dont conpletely understand how to start. if you could provide a code with some steps id appreciate it.

Answer 1

Since you have not mentioned the language of your preference, I am providing the code in JAVA.

CODE

import java.util.LinkedList;

public class AdjacencyList

{

static class Graph

{

int V;

LinkedList<Integer> adjListNodes[];

// constructor

Graph(int V)

{

this.V = V;

// define the size of array as

// number of vertices

adjListNodes = new LinkedList[V];

// Create a new list for each vertex

// such that adjacent nodes can be stored

for(int i = 0; i < V ; i++){

adjListNodes[i] = new LinkedList<>();

}

}

}

public static void addEdge(Graph graph, int src, int dest)

{

graph.adjListNodes[src].add(dest);

// Since this is an undirected graph, need to add an edge from dest to src too

graph.adjListNodes[dest].add(src);

}

public static void displayGraph(Graph graph)

{

for(int v = 0; v < graph.V; v++)

{

System.out.println("Adjacency list of vertex "+ v);

System.out.print("head");

for(Integer pCrawl: graph.adjListNodes[v]){

System.out.print(" -> "+pCrawl);

}

System.out.println("\n");

}

}

public static void main(String args[])

{

// create the graph given in above figure

int V = 5;

Graph graph = new Graph(V);

addEdge(graph, 0, 1);

addEdge(graph, 0, 2);

addEdge(graph, 1, 3);

addEdge(graph, 1, 2);

addEdge(graph, 1, 0);

addEdge(graph, 2, 3);

addEdge(graph, 3, 4);

displayGraph(graph);

}

}