public class FloydTest {
 private static int[][] matrix;

 private static int[][] path;

 public static void main(String[] args) {

  initMatrixAndPath(
      new int[][]{
          {0, 1, 8, 5},
          {1, 0, 7, 6},
          {8, 7, 0, 2},
          {5, 6, 2, 0}}
  );


  floyd(matrix, path);
  printShortDistance();
  printShortDistanceDetail();
 }

 private static void initMatrixAndPath(int[][] matrix) {
  FloydTest.matrix = matrix;
  FloydTest.path = new int[matrix.length][matrix.length];

  for (int i = 0; i < FloydTest.matrix.length; i++) {
   for (int j = 0; j < FloydTest.matrix[i].length; j++) {
    path[i][j] = j;
   }
  }
 }

 private static void floyd(int[][] matrix, int[][] path) {
  for (int k = 0; k < matrix.length; k++) {
   for (int i = 0; i < matrix.length; i++)
    for (int j = 0; j < matrix.length; j++) {
     if (matrix[i][j] > matrix[i][k] + matrix[k][j]) {
      matrix[i][j] = matrix[i][k] + matrix[k][j];
      path[i][j] = path[i][k];
     }
    }
  }


 }

 private static String getNodeName(int nodeIndex) {
  return "v" + nodeIndex;
 }

 private static void printShortDistanceDetail() {
  for (int i = 0; i < matrix.length; i++) {
   for (int j = 0; j < matrix[i].length; j++) {
    int x = j;
    StringBuilder sb = new StringBuilder("最短路徑[v" + i + ",v" + j + "]為:");
    sb.append(getNodeName(x));
    sb.append("<--");
    while (path[i][j] != x) {
     x = path[i][x];
     sb.append(getNodeName(path[i][x]));
     sb.append("<--");
    }
    sb.append(getNodeName(i));

    System.out.println(sb);
   }

  }
 }

 private static void printShortDistance() {
  for (int i = 0; i < matrix.length; i++) {
   for (int j = 0; j < matrix[i].length; j++) {
    System.out.println("v" + i + "到" + "v" + j + "最短路徑為:" + matrix[i][j]);
   }
  }
 }
}