Question

Creating Graphs First, write Java code in GraphTest.java to read a data file (graph.in) and create a graph using the input data. The input file must have the following format: 6 049 0 27 2 3 1 25 2 1 5 6 352 4 5 1 Here, the number on the first line represents the number of vertices in the graph. The letter on the second line indicates whether this is a directed graph ('D') or an undirected graph ('U'). The remainder of the input file must contain one or more lines of the form (i, j, w), which represents a weighted edge between vertex i and j with the weight w. Use Scanner class to read in the data file as follows: Scanner sc = new Scanner(new File("graph.in")); Using various methods defined in Graphm.java, create a graph which includes all vertices and edges defined in the data file.

Answer 1

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Solution :-

Java Code :-

import java.io.*;
import java.util.*;

class GraphTest
{
   int numVertex;   // number of vertices
   char graph;       // 'U' -> if undirected, 'D' -> if directed graph
   int[][] adj;   //2-D matrix to represent graph adj[i][j] -> weight of edge (i,j)
   public void read() throws Exception
   {

       // reading data from file using scanner
       Scanner sc = new Scanner(new File("graph.in"));

       numVertex = sc.nextInt();

       adj = new int[numVertex][numVertex];

       graph = sc.next().charAt(0);

       while(sc.hasNext())
       {
           int u,v,w;

           u = sc.nextInt();
           v = sc.nextInt();
           w = sc.nextInt();

           adj[u][v] = w;

           if(graph == 'U')
               adj[v][u] = w;

       }
   }

   public void print()
   {
       System.out.println("printing graph in form adjacency matrix :- ");

       for(int i=0;i<numVertex;i++)
       {
           for(int j=0;j<numVertex;j++)
               System.out.print(adj[i][j] + " ");

           System.out.print("\n");
       }
   }
   public static void main(String args[]) throws Exception
   {
       GraphTest obj = new GraphTest();

       obj.read();

       obj.print();
   }
}

Sample output :-

printing graph in form adjacency matrix :-
0 3 0 5 1
3 0 4 0 0
0 4 0 0 8
5 0 0 0 0
1 0 8 0 0