java – 动态编程ArrayIndexOutOfBoundException

我得到了这个奇怪的异常,我真的不明白为什么..我试过调试,发现运行时出错了：

opt[i][j] = Double.POSITIVE_INFINITY; 

当i == 0且j == 1时,但这不应该发生,因为在这种情况下,opt是9×6矩阵.

这是我的代码：

public class Versie3 {

    private int desCap;
    private int currentCap;
    private int maxCap;
    private int timeSlot;
    private static ArrayList<Double> prices;
    private double[][] opt = new double[timeSlot + 1][maxCap + 1];

    public Versie3() throws FileNotFoundException {

    }

    public void readInput(String s) throws FileNotFoundException 
    {
        FileReader fr = new FileReader(s);
        Scanner sc = new Scanner(fr);

        timeSlot = sc.nextInt();
        maxCap = sc.nextInt();
        currentCap = sc.nextInt();
        desCap = sc.nextInt();
        prices = new ArrayList<Double>(timeSlot);

        while (sc.hasNextDouble()) {
            prices.add(sc.nextDouble());

        }
    }

    public double calculateOptimal() 
    {
        for (int i = 0; i <= timeSlot; i++) 
        {
            for (int j = 0; j <= maxCap; j++) 
            {
                if (i == 0) 
                {
                    if (j != desCap) 
                    {

                        opt[i][j] = Double.POSITIVE_INFINITY; // <--here it goes Wrong!
                    } 
                    else 
                    {
                        opt[i][j] = 0;
                    }
                } 
                else if (j == 0) 
                {
                    opt[i][j] = Math.min(opt[i - 1][j],
                            opt[i - 1][j + 1]
                                    - prices.get(i-1));
                } 
                else if (j == maxCap) 
                {
                    opt[i][j] = Math.min(opt[i - 1][j],
                            opt[i - 1][j - 1]
                                    + prices.get(i-1));
                } 
                else 
                {
                    opt[i][j] = Math.min(Math.min(opt[i - 1][j],
                    opt[i - 1][j - 1]
                    + prices.get(i - 1)),opt[i - 1][j + 1]- prices.get(i-1));
                }
            }
        }
        return opt[timeSlot][currentCap];
    }

    public static void main(String[] args) throws FileNotFoundException {
        Versie3 v3 = new Versie3();
        v3.readInput("input.txt");
        System.out.println("prices: " + prices.toString());
        System.out.println("timeSlot: " + v3.timeSlot);
        System.out.println("maxCap: " + v3.maxCap);
        System.out.println("currentCap: " + v3.currentCap);
        System.out.println("desCap: " + v3.desCap);
        //System.out.println("minimum cost: "+v3.calculateOptimal());
        System.out.println(v3.prices.size());

    }

}

这是我正在阅读的输入文件：

8 5 2 5
2.2 3 5 6.5 5 5 3 1.8

在这种情况下：

timeSlot = 8
maxCap = 5
currentCap = 2 
desCap = 5

第二行显示每个时段的价格.总共8个.

感谢任何帮助.

解决方法:

您正在使用maxCap和timeSlot创建数组,而它们的默认值仍为0. readInput()尚未调用,那么您怎么知道制作数组的大小？

在读入maxCap和timeSlot后创建数组.

标签：java,dynamic-programming
来源： https://codeday.me/bug/20190730/1579380.html