C# 单链表求和方法

Question

我想求一个简单列表的总和。但我无法创建没有参数的方法 Sum() 。请提出可能的解决方案。

void Main()
{
    var chain1 = new Add(5)).Append(new Add(10)).Append(new add(15));
    var sum = chain.Sum();
}

public abstract class Strategy
{
    private Strategy _next;
    public Strategy Append(Strategy next)
    {
        if(_next == null){
            _next = next;
        } else {
            _next.Append(next);
        }
        
        return this;
    }
}

public class Add : Strategy
{
    int _num;
    public Add(int num) => _num = num;
    
    public int Sum()
    {
      ....
    }
}

Answer 1

@marsze 是正确的，有更好的方法可以做到这一点......但我能够对其进行一些修改，最终得到了这个非战斗强化的代码:

public abstract class Strategy
{
    protected Strategy _next;

    public Strategy Append(Strategy next)
    {
        if (_next == null)
        {
            _next = next;
        }
        else
        {
            _next.Append(next);
        }

        return this;
    }

    public abstract int Sum();
}

public class Add : Strategy
{
    int _num;
    public Add(int num) => _num = num;

    public override int Sum()
    {
        if (_next == null)
        {
            return _num;
        }

        return _num + _next.Sum();
    }
}