链表方法中的错误 [英] Errors in linked list methods

问题描述

我在C#中的代码有问题.如果单击编译器"按钮，则会出现以下错误

I have a problem with my code in C# . if i click in compiler button , I get the following errors

The best overloaded method match for System.Collections.Generic.LinkedList<int?>.AddFirst(int?)'' has some invalid arguments, System.Collections.Generic.LinkedList<int?>'' does not contain a definition for  Element and no extension method  Element accepting a first argument of type System.Collections.Generic.LinkedList<int? could be found (are you missing a using directive or an assembly reference?) and Argument 1 cannot convert from void to int? 

这是我程序的一部分

This is apart of my program

using System.;

    using System.Collections.Generic;
    using System.Linq;
    using System.Text;

    namespace Hanoi_tower
    {
       public class Sol
        {

    public LinkedList<int?> tower1 = new LinkedList<int?>();
       public LinkedList<int?> tower2 =new LinkedList<int?>();
       public LinkedList<int?> tower3 =new LinkedList<int?>();
       public int depth;

       public LinkedList<Sol> neighbors;

        public Sol(LinkedList<int?> tower1, LinkedList<int?> tower2, LinkedList<int?> tower3)
        {
            this.tower1 = tower1;
            this.tower2 = tower2;
            this.tower3 = tower3;

            neighbors = new LinkedList<Sol>();
        }

        public virtual void getneighbors()
        {

            Sol temp = this.copy();
            Sol neighbor1 = this.copy();
            Sol neighbor2 = this.copy();
            Sol neighbor3 = this.copy();
            Sol neighbor4 = this.copy();
            Sol neighbor5 = this.copy();
            Sol neighbor6 = this.copy();


            if (temp.tower1.Count != 0)
            {

                if (neighbor1.tower2.Count != 0)
                {
                    if (neighbor1.tower1.First.Value < neighbor1.tower2.First.Value)
                    {
                        neighbor1.tower2.AddFirst(neighbor1.tower1.RemoveFirst);
                        neighbors.AddLast(neighbor1);
                    }

                }
                else
                {
                    neighbor1.tower2.AddFirst(neighbor1.tower1.RemoveFirst());
                    neighbors.AddLast(neighbor1);
                }



                if (neighbor2.tower3.Count != 0)
                {
                    if (neighbor2.tower1.First.Value < neighbor2.tower3.First.Value)
                    {
                        neighbor2.tower3.AddFirst(neighbor2.tower1.RemoveFirst());
                        neighbors.AddLast(neighbor2);
                    }
                }
                else
                {
                    neighbor2.tower3.AddFirst(neighbor2.tower1.RemoveFirst());
                    neighbors.AddLast(neighbor2);
                }

            }




            //-------------

            if (temp.tower2.Count != 0)
            {


                if (neighbor3.tower1.Count != 0)
                {
                    if (neighbor3.tower2.First.Value < neighbor3.tower1.First.Value)
                    {
                        neighbor3.tower1.AddFirst(neighbor3.tower2.RemoveFirst());
                        neighbors.AddLast(neighbor3);
                    }
                }
                else
                {
                    neighbor3.tower1.AddFirst(neighbor3.tower2.RemoveFirst());
                    neighbors.AddLast(neighbor3);
                }



                if (neighbor4.tower3.Count != 0)
                {
                    if (neighbor4.tower2.First.Value < neighbor4.tower3.First.Value)
                    {
                        neighbor4.tower3.AddFirst(neighbor4.tower2.RemoveFirst());
                        neighbors.AddLast(neighbor4);
                    }
                }
                else
                {
                    neighbor4.tower3.AddFirst(neighbor4.tower2.RemoveFirst());
                    neighbors.AddLast(neighbor4);
                }


            }

我真的不知道哪里出了问题.请帮忙，

I really dont know where it went wrong. Please help,

推荐答案

这是因为您没有为AddFirst方法提供正确的参数类型. AddFirst方法是否期望为int?作为一个论点.您正在提供RemoveFirst方法作为参数，其返回类型为void而不是int?.

That is because you are not providing correct argument type to the AddFirst method. AddFirst method is expecting a int? as an argument. You are providing RemoveFirst method as an argument which has a return type of void and not int?.

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