Question

所以我有这本图表，我正在迭代并打印出来。

public class Books : IBookFinder
{
    private Books(Books next, string book)
    {
        Next = next;
        Book = book;
    }

    public Books Next { get; }
    public string Book { get; }

    public Books Previous(string book)
    {
        return new Books(this, book);
    }

    public static Books Create(string book)
    {
        return new Books(null, book);
    }

    //This is the method I'm especially interested in implementing
    public string FromLeft(Books books, int numberFromLeft)
    {
        Console.Writeline("This is FromLeft method");
    }
}

一切都很好，但是我想实现FromLeft方法，这样我就可以根据数字输入从图中的位置写出书的名称。例如，如果输入＆＃34; 3＆＃34;，则应输出＆＃34; Twilight＆＃34;。

class Program
{
    static void Main(string[] args)
    {
        var curr = Books
            .Create("Harry Potter")
            .Previous("Lord of the Rings")
            .Previous("Twilight")
            .Previous("Da Vinci Code");

        while (curr != null)
        {
            if (curr.Next != null)
            {
                Console.Write(curr.Book + " --- ");
            }
            else
            {
                Console.WriteLine(curr.Book);
            }
            curr = curr.Next;
        }

        Console.WriteLine("Input number to pick a book");

        var bookNumber = Console.ReadLine();
        int n;

        if (int.TryParse(bookNumber, out n)) //Checking if the input is a #
        {

        }
        else
        {
            Console.WriteLine("Input was not a number!");
        }
        Console.WriteLine(bookNumber);

        Console.ReadLine();
    }
}

有关我如何处理此事的任何提示？

Answer 1

创建一个方法，通过书本x次迭代。

private Books FromLeft(Books book, int x){
    for(var i = 1; i < x; i++){
        book = book?.next;  // Check for null if you're not using C#6
    }
    return book;
}

如果你拿错了书，你可能需要更改一些数字。

递推!!!洛尔

private Books FromLeft(Books book, int x){
    if(x-- > 0) return FromLeft(book?.Next, x); // Check for null if you're not using C#6
    return book;
}

要获得前一个:(我不知道让你的班级静止是多么困难）

public static class Books : IBookFinder
{
    private Books(Books next, string book, Books previous)
    {
        Next = next;
        Book = book;
        Previous = previous;
    }

    public Books Next { get; }
    public Books Previous { get; }
    public string Book { get; }

    public static Books Previous(this Books previous, string book)
    {
        return new Books(this, book, previous);
    }

    public static Books Create(string book)
    {
        return new Books(null, book, null);
    }

    private Books FromLeft(Books book, int x){
        if(x-- > 0) return FromLeft(book?.Next, x); // Check for null if you're not using C#6
        return book;
    }

    private Books FromRight(Books book, int x){
        if(x-- > 0) return FromRight(book?.Previous, x); // Check for null if you're not using C#6
        return book;
    }
}

在一系列线性书中找到第n本书

1 个答案: