因为需求需要，所以直接写一个数据结构

直接上代码：

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

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            MyList<int> m = new MyList<int>();
            m.add(1);
            m.add(2);
            m.add(3);
            Console.WriteLine(m.getAndRemoveLast());
            Console.WriteLine(m.getAndRemoveFirst());
            Console.WriteLine(m.getAndRemoveLast());
            
            Console.WriteLine(m.getAndRemoveLast());
            Console.WriteLine(m.getAndRemoveLast());
            m.add(3);
            Console.WriteLine(m.getAndRemoveFirst());
            m.add(4);
            m.add(5);
            m.add(6);
            m.add(7);
            m.add(8);
            Console.WriteLine(m.getAndRemoveLast());
            Console.WriteLine(m.getAndRemoveLast());
            Console.WriteLine(m.getAndRemoveFirst());
            Console.WriteLine(m.getAndRemoveFirst());
            Console.Read();
        }
    }

    //c#的集合太傻逼了，在此自制链表
    class MyList<T>
    {
        public int count;//总数
        public Node<T> first;//头节点
        public Node<T> last;//尾节点
        //添加函数
        public void add(T t)
        {
            if (first == null)
            {
                first = new Node<T>(t);
                last = first;
            }
            else
            {
                Node<T> node = new Node<T>(t);
                node.next = first;
                first.prev = node;
                first = node;
            }
            count++;
        }
        /**
         * 获取并删除最后一个元素
         * **/
        public T getAndRemoveLast()
        {
            Node<T> las = last;
            if(last!=null)
            {
                count--;
                if (first == last)
                {
                    last = null;
                    first = last;
                    return las.t;
                }
                else
                {
                    last = last.prev;
                    las.prev = null;
                    last.next = null;
                    return las.t;
                }
            }
            else
            {
                return default(T);
            }
        }


        /**
         * 获取并删除第一个元素
         * **/
        public T getAndRemoveFirst()
        {
            Node<T> fir = first;
            if (first != null)
            {
                count--;
                if (first == last)
                {
                    last = null;
                    first = last;
                    return fir.t;
                }
                else
                {
                    first = first.next;
                    fir.next = null;
                    first.prev = null;
                    return fir.t;
                }
            }
            else
            {
                return default(T);
            }
        }
    }
	//节点类
    class Node<T>
    {
        public Node<T> next;
        public Node<T> prev;
        public T t;
        public Node(T t)
        {
            this.t = t;
            next = null;
            prev = null;
        }
    }
}