Question

我的代码正在返回Runtime error，但我不知道如何解决这个问题。这段代码是关于问题104.我试图改变一些事情，但没有...我读到了这个错误，基本上与扫描仪有关。请帮帮我！

import java.util.Scanner;

public class Main {

    static int MAX = 20;
    static double LUCRO_MIN = 1.01;

    public static void main(String[] args) {
        Scanner sc = new Scanner (System.in);
        int n, i, j;
        double v;
        while(sc.hasNext()) {
            double[][] W = new double [MAX][MAX];
            n = sc.nextInt();
            sc.nextLine();
            for(i = 0; i < n; i++) {
                int pos = 0;
                String linha = sc.nextLine();
                String vertice[] = linha.split(" ");
                for(j = 0; j < n; j++) {
                    if(i == j) {
                        W[i][i] = 0;
                        continue;
                    }
                    v = Double.parseDouble(vertice[pos]);
                    W[i][j] = v;
                    pos++;
            }
          }
        Converte(n, W);
      }
    }

    static public void Imprime (int i, int j, int l, int P[][][]) {
      if(l == 0)
        System.out.printf ("%d\n", i + 1);
      else {
        System.out.printf ("%d ", i + 1);
        Imprime (P[l][i][j], j, l - 1, P);
      }
    }

    static void IniZero (int n, double m[][][], int l) {
      int i, j;
      for(i = 0; i < n; i++)
        for(j = 0; j < n; j++)
          m[l][i][j] = 0;
    }

    static void Converte(int n, double W[][]) {
      double[][][] B = new double [MAX][MAX][MAX];
      int [][][]P = new int [MAX][MAX][MAX];
      int l, i, j, k;
      for(i = 0; i < n; i++)
        for(j = 0; j < n; j++) {
          B[1][i][j] = W[i][j];
          if(W[i][j] > 0)
            P[1][i][j] = j;
        }
      for(l = 2; l <= n; l++) {
        IniZero(n, B, l);
        for(i = 0; i < n; i++)
          for(j = 0; j < n; j++)
            for(k = 0; k < n; k++) {
              if(B[l][i][j] < W[i][k] * B[l - 1][k][j]) {
                B[l][i][j] = W[i][k] * B[l - 1][k][j];
                P[l][i][j] = k;
                if(B[l][i][i] >= LUCRO_MIN) {
                  Imprime(i, i, l, P);
                  return;
                }
              }
            }
      }
      System.out.printf("no arbitrage sequence exists\n");
    }
}

Answer 1

像这样更换扫描仪

Scanner input = new Scanner(System.in);

以

Scanner input = new Scanner(new FileInputStream(args[0]));

我建议您使用input.hasNext()代替input.nextInt();，这可能导致nullpointerexception

运行时错误UVA

1 个答案: