private void floydWarshall() {
            for (int k = 0; k < d.length; k++) {
                for (int i = 0; i < d.length; i++) {
                    for (int j = i; j < d.length; j++) {
                        if (d[i][k] == Float.MAX_VALUE
                                || d[k][j] == Float.MAX_VALUE) {
                            continue;
                        }
                        if (d[i][j] > d[i][k] + d[k][j]) {
                            d[i][j] = d[j][i] = d[i][k] + d[k][j];
                        }
                    }
                }
            }
    }