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Thread: Adjacency list graph

  1. #1
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    Default Adjacency list graph

    I'm trying to read a text file of a graph and print information about the graph including the order and size of the graph, rather it is a directed or undirected graph, if it is directed the in and out degree, and the and a list of all vertices for which it is adjacent. The problem is the adjacency list is just printing out the list of vertices instead of the adjacency list. Is there something in my code that is problematic? Also I'm unsure of how to go about the in and out degree do you guys have any ideas?

    "graphs.txt"
    6,1
    0,2 0,4 1,4 1,5 2,1 2,3 2,5 3,2 3,4 4,1 4,5 5,1 5,3 5,2

    import java.io.File;
    import java.io.FileNotFoundException;
    import java.util.Scanner;
     
    public class AdjList {
        private Node first;        // beginning of list
        private int N;             // size of list
     
        // helper linked list data type
        private static class Node {
            String name;
            Node next;
            Node(String name, Node next) {
                this.name = name;
                this.next = next;
            }
        }
     
        public boolean isEmpty() { return (first == null); }
        public int size()        { return N; }
     
        // add s to the adjacency list
        public void insert(String s) {
            first = new Node(s, first);
            N++;
        }
     
        // return string representation of list (in reverse order of list)
        public String toString() {
            String s = "";
            for (Node x = first; x != null; x = x.next)
                s = x.name + "-> " + s;
            return "{ " + s+"->" + "}";
        }
     
        // return array of strings comprising this adjacency list
        public String[] toArray() {
            String[] names = new String[N];
            int i = N;
            for (Node x = first; x != null; x = x.next)
                names[--i] = x.name;
            System.out.println(names);
            return names;
        }
     
     
     
        public static void main(String[] args) throws FileNotFoundException {
     
            AdjList adjlist = new AdjList();
            Scanner sc = new Scanner(new File("graphs.txt"));
     
     
     
     
            String line = sc.nextLine();
    	    String[] data=line.split("[\\,]");
    	    int order=Integer.parseInt(data[0]);
     
    	    int typeOfGraph=Integer.parseInt(data[1]);
    	  //Prints results of the order
    	    System.out.println("The order of the graph = " + order);
    	    while(sc.hasNext())
    	    {
    	    	line=sc.nextLine();
    	    	int index =0;
    	    	int count=0;
    	        char edges = ',';
    	        while(index<line.length()) {
     
    	            if(line.charAt(index)==edges){
    	                count++;
    	            }
    	            index++;
    	        }
    	        /* PRINTS the result for each line!!! */
    	        System.out.println("The size of graph = "+count);
     
     
    	        //Determines if graph is zero or one
     
    		    String[] data2=line.split("[\\|]");
    	        String[][] vertices = new String[ data2.length ][];
    	        for (int i = 0; i < data2.length; i++){
    	        	vertices[i] = data2[i].split("[ ]");
    	        }
     
    	        count=0;
    	        index=0;
    	        System.out.println("Graph: ");
    	        int i=0;
    	        int j=0;
     
    	        for ( j = 0; j < vertices.length; j++){
    	        	for ( i = 0; i < vertices[j].length; i++){
     
    	 	        	System.out.print("Index "+i+": "+vertices[j][i]+" \n");
     
     
     
    	        	}
    	        }
    	        if(typeOfGraph==1)
    	        {
    	        	System.out.println("Graph is a directed graph");
     
    	        }
    	        if(typeOfGraph==0)
    	        {
    	        	System.out.println("Graph is a undirected graph");
    	        }
    	System.out.println("Adjacency List");
            adjlist.insert(line);
            System.out.println(adjlist);
        }
        }
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Adjacency list graph

    list of vertices instead of the adjacency list.
    Can you explain the difference and show an example?
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
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    Default Re: Adjacency list graph

    Yes here's the output:


    The order of the graph = 6
    The size of graph = 14
    Graph:
    Index 0: 0,2
    Index 1: 0,4
    Index 2: 1,4
    Index 3: 1,5
    Index 4: 2,1
    Index 5: 2,3
    Index 6: 2,5
    Index 7: 3,2
    Index 8: 3,4
    Index 9: 4,1
    Index 10: 4,5
    Index 11: 5,1
    Index 12: 5,3
    Index 13: 5,2
    Graph is a directed graph
    Adjacency List
    { 0,2 0,4 1,4 1,5 2,1 2,3 2,5 3,2 3,4 4,1 4,5 5,1 5,3 5,2-> ->}

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: Adjacency list graph

    OK, explain what is wrong with it and post what it should look like.
    If you don't understand my answer, don't ignore it, ask a question.

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