import static java.lang.String.format;
import java.util.Arrays;

public class FloydWarshall {

    public static void main(String[] args) {
        int[][] weights = {{1, 3, -2}, {2, 1, 4}, {2, 3, 3}, {3, 4, 2}, {4, 2, -1}};
        int numVertices = 4;

        floydWarshall(weights, numVertices);
    }

    static void floydWarshall(int[][] weights, int numVertices) {

        double[][] dist = new double[numVertices][numVertices];
        for (double[] row : dist)
            Arrays.fill(row, Double.POSITIVE_INFINITY);

        for (int[] w : weights)
            dist[w[0] - 1][w[1] - 1] = w[2];

        int[][] next = new int[numVertices][numVertices];
        for (int i = 0; i < next.length; i++) {
            for (int j = 0; j < next.length; j++)
                if (i != j)
                    next[i][j] = j + 1;
        }

        for (int k = 0; k < numVertices; k++)
            for (int i = 0; i < numVertices; i++)
                for (int j = 0; j < numVertices; j++)
                    if (dist[i][k] + dist[k][j] < dist[i][j]) {
                        dist[i][j] = dist[i][k] + dist[k][j];
                        next[i][j] = next[i][k];
                    }

        printResult(dist, next);
    }

    static void printResult(double[][] dist, int[][] next) {
        System.out.println("pair     dist    path");
        for (int i = 0; i < next.length; i++) {
            for (int j = 0; j < next.length; j++) {
                if (i != j) {
                    int u = i + 1;
                    int v = j + 1;
                    String path = format("%d ->%d   %2d    %s", u, v,
                            (int) dist[i][j], u);
                    do {
                        u = next[u - 1][v - 1];
                        path += " -> " + u;
                    } while (u != v);
                    System.out.println(path);
                }
            }
        }
    }
}