102 lines
4.0 KiB
Java
102 lines
4.0 KiB
Java
|
/*This Java program is to implement the Floyd-Warshall algorithm.The algorithm is a graph analysis algorithm for finding shortest paths in a weighted graph with positive or negative edge weights (but with no negative cycles) and also for finding transitive closure of a relation R.*/
|
||
|
|
|
||
|
|
import java.util.Scanner;
|
||
|
|
|
||
|
|
public class FloydWarshall
|
||
|
|
{
|
||
|
|
private int distancematrix[][];
|
||
|
|
private int numberofvertices;
|
||
|
|
public static final int INFINITY = 999;
|
||
|
|
|
||
|
|
public FloydWarshall(int numberofvertices)
|
||
|
|
{
|
||
|
|
distancematrix = new int[numberofvertices + 1][numberofvertices + 1];
|
||
|
|
this.numberofvertices = numberofvertices;
|
||
|
|
}
|
||
|
|
|
||
|
|
public void floydwarshall(int adjacencymatrix[][])
|
||
|
|
{
|
||
|
|
for (int source = 1; source <= numberofvertices; source++)
|
||
|
|
{
|
||
|
|
for (int destination = 1; destination <= numberofvertices; destination++)
|
||
|
|
{
|
||
|
|
distancematrix[source][destination] = adjacencymatrix[source][destination];
|
||
|
|
}
|
||
|
|
}
|
||
|
|
for (int intermediate = 1; intermediate <= numberofvertices; intermediate++)
|
||
|
|
{
|
||
|
|
for (int source = 1; source <= numberofvertices; source++)
|
||
|
|
{
|
||
|
|
for (int destination = 1; destination <= numberofvertices; destination++)
|
||
|
|
{
|
||
|
|
if (distancematrix[source][intermediate] + distancematrix[intermediate][destination]
|
||
|
|
< distancematrix[source][destination])
|
||
|
|
distancematrix[source][destination] = distancematrix[source][intermediate]
|
||
|
|
+ distancematrix[intermediate][destination];
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
for (int source = 1; source <= numberofvertices; source++)
|
||
|
|
System.out.print("\t" + source);
|
||
|
|
System.out.println();
|
||
|
|
for (int source = 1; source <= numberofvertices; source++)
|
||
|
|
{
|
||
|
|
System.out.print(source + "\t");
|
||
|
|
for (int destination = 1; destination <= numberofvertices; destination++)
|
||
|
|
{
|
||
|
|
System.out.print(distancematrix[source][destination] + "\t");
|
||
|
|
}
|
||
|
|
System.out.println();
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
public static void main(String... arg)
|
||
|
|
{
|
||
|
|
int adjacency_matrix[][];
|
||
|
|
int numberofvertices;
|
||
|
|
Scanner scan = new Scanner(System.in);
|
||
|
|
System.out.println("Enter the number of vertices");
|
||
|
|
numberofvertices = scan.nextInt();
|
||
|
|
adjacency_matrix = new int[numberofvertices + 1][numberofvertices + 1];
|
||
|
|
System.out.println("Enter the Weighted Matrix for the graph");
|
||
|
|
for (int source = 1; source <= numberofvertices; source++)
|
||
|
|
{
|
||
|
|
for (int destination = 1; destination <= numberofvertices; destination++)
|
||
|
|
{
|
||
|
|
adjacency_matrix[source][destination] = scan.nextInt();
|
||
|
|
if (source == destination)
|
||
|
|
{
|
||
|
|
adjacency_matrix[source][destination] = 0;
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
if (adjacency_matrix[source][destination] == 0)
|
||
|
|
{
|
||
|
|
adjacency_matrix[source][destination] = INFINITY;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
System.out.println("The Transitive Closure of the Graph");
|
||
|
|
FloydWarshall floydwarshall = new FloydWarshall(numberofvertices);
|
||
|
|
floydwarshall.floydwarshall(adjacency_matrix);
|
||
|
|
scan.close();
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
Enter the number of vertices
|
||
|
|
4
|
||
|
|
|
||
|
|
Enter the Weighted Matrix for the graph
|
||
|
|
0 0 3 0
|
||
|
|
2 0 0 0
|
||
|
|
0 7 0 1
|
||
|
|
6 0 0 0
|
||
|
|
|
||
|
|
The Transitive Closure of the Graph
|
||
|
|
|
||
|
|
1 2 3 4
|
||
|
|
1 0 10 3 4
|
||
|
|
2 2 0 5 6
|
||
|
|
3 7 7 0 1
|
||
|
|
4 6 16 9 0
|