c# - 归并排序问题

Question

我正在制作各种排序算法的菜单，现在我陷入了归并排序。单击执行按钮后遇到错误。我在 TextBox1 中输入了 5 个数字，在 TextBox2 中输入了另一组 5 个数字。它说索引超出了数组的范围。我在代码上指出了它出现的位置。有什么想法吗？

    private void ExeButton_Click(object sender, EventArgs e)
    {
        string[] numsInString = EntNum.Text.Split(' ');   //split values in textbox
        string[] numsInString1 = EntNum1.Text.Split(' ');
        for (int j = 0; j < numsInString.Length; j++)
        {
            a[j] = int.Parse(numsInString[j]);
        }
        for (int j = 0; j < numsInString1.Length; j++)
        {
            b[j] = int.Parse(numsInString1[j]);
        }
        {
            sortArray();
            Display();
        }

    }

    public void sortArray()
    {
        m_sort(0, 10 - 1);
    }

    public void m_sort(int left, int right)
    {
        int mid;

        if (right > left)
        {
            mid = (right + left) / 2;
            m_sort(left, mid);
            m_sort(mid + 1, right);

            merge(left, mid + 1, right);
        }
    }

    public void merge(int left, int mid, int right)
    {
        int i, left_end, num_elements, tmp_pos;

        left_end = mid - 1;
        tmp_pos = left;
        num_elements = right - left + 1;

        while ((left <= left_end) && (mid <= right))
        {
            if (a[left] <= a[mid])  //index was outside the bounds of the the array
            {
                b[tmp_pos] = a[left];
                tmp_pos = tmp_pos + 1;
                left = left + 1;
            }
            else
            {
                b[tmp_pos] = a[mid];
                tmp_pos = tmp_pos + 1;
                mid = mid + 1;
            }
        }

        while (left <= left_end)
        {
            b[tmp_pos] = a[left];
            left = left + 1;
            tmp_pos = tmp_pos + 1;
        }

        while (mid <= right)
        {
            b[tmp_pos] = a[mid];
            mid = mid + 1;
            tmp_pos = tmp_pos + 1;
        }

        for (i = 0; i < num_elements; i++)
        {
            a[right] = b[right];
            right = right - 1;
        }
    }


    private void ClearButton_Click(object sender, EventArgs e)
    {
        richTextBox1.Clear();
    }

    public void Display()
    {
        int i;
        String numbers = "";
        for (i = 0; i < 10; i++)
        numbers += a[i].ToString() + "       ";
        numbers += b[i].ToString() + "       ";
        richTextBox1.AppendText(numbers + "\n");
    }

Answer 1

关于您的具体问题:a 是一个包含 5 个元素的数组，索引为 0, 1, 2, 3, 4，所以 a[4] 是最后一个元素。您从 m_sort(0, 10 - 1) = m_sort(0, 9); 开始。在 m_sort() 中你计算

mid = (right + left) / 2 = (9 + 0) / 2 = 4

然后打电话

merge(left, mid + 1, right) = merge(0, 4 + 1, 9) = merge(0, 5, 9).

在 merge(int left, int mid, int right) 中你计算:

if (a[left] <= a[mid])   i.e.     if (a[0] <= a[5]) 

因此您访问了越界的 a[5]。

我认为您的合并排序可以大大简化。您可能会查看 Web 上的许多资源或有关算法的教科书。