floyd_algo.java

import java.util.Scanner;

public class FloydsClass {
    static final int MAX = 20;
    static int a[][];
    static int n;

    public static void main(String args[]) {
        a = new int[MAX][MAX];
        ReadMatrix();
        Floyds();
        PrintMatrix();
    }

    static void ReadMatrix() {
        System.out.println("Enter the number of vertices\n");
        Scanner scanner = new Scanner(System.in);
        n = scanner.nextInt();
        System.out.println("Enter the Cost Matrix (999 for infinity) \n");
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                a[i][j] = scanner.nextInt();
            }
        }
        scanner.close();
    }

    static void Floyds() {
        for (int k = 1; k <= n; k++) {
            for (int i = 1; i <= n; i++)
                for (int j = 1; j <= n; j++)
                    if ((a[i][k] + a[k][j]) < a[i][j])
                        a[i][j] = a[i][k] + a[k][j];
        }
    }

    static void PrintMatrix() {
        System.out.println("The All Pair Shortest Path Matrix is:\n");
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++)
                System.out.print(a[i][j] + "\t");
            System.out.println("\n");
        }
    }
}