class MyList : List<int>, IComparable<MyList>
    {
        public MyList(List<int> lst)
        {
            if(lst != null)
                AddRange(lst);
        }
        public static MyList operator+(MyList left, MyList right)
        {
            MyList list = new MyList(left);
            list.AddRange(right);
            return list;
        }
        public static MyList operator *(MyList left, int numOfCopies)
        {
            MyList list = new MyList(left);
            while(numOfCopies != 1)
            {
                list.AddRange(left);
                numOfCopies--;
            }
            return list;
        }
        public MyList SubList(int start, int stop = 0, int step = 1)
        {
            if (start < 0)
                start = Count + start;
            if (stop < 0)
                stop = Count + stop;
            if (step == 0)
                throw new ArgumentException("step不可为负数");
            MyList result = new MyList(null);
            if (step > 0)
            {
                for (int i = start; i < stop; i+=step)
                {
                    result.Add(this[i]);
                }
            }
            else
            {
                for (int i = start ; i > stop; i += step)
                {
                    result.Add(this[i]);
                }
            }
            return result;
        }
        public override string ToString()
        {
            StringBuilder result = new StringBuilder("[");
            for (int i = 0; i < Count; i++)
            {
                result.Append(this[i]);
                if (i != Count - 1)
                    result.Append(", ");
            }
            result.Append("]");
            return result.ToString();
        }

        public int CompareTo(MyList? other)
        {
            if (other == null)
                throw new ArgumentNullException("Argument null in CompareTo");
            int size = (Count < other.Count) ? Count : other.Count;
            for (int i = 0; i < size; i++)
            {
                if (this[i] != other[i])
                    return this[i] - other[i];
            }
            return Count - other.Count;
        }
    }
    class Ex4 : Object
    {
        public static void Main()
        {
            List<int> lst = new List<int>() { 1, 4, 9, 6, 3, 5};
            WriteLine(lst);
            MyList lst1 = new MyList(lst);
            WriteLine("1: " + lst1);
            MyList lst2 = lst1 * 2;
            WriteLine("2: " + lst2);
            MyList lst3 = lst2.SubList(4, 8);
            WriteLine("3 从4到8: " + lst3);
            MyList lst4 = lst2.SubList(4, 8, 2);
            WriteLine("4 从4到8步长2: " + lst4);
            MyList lst5 = lst2.SubList(-2, 1, -3);
            WriteLine("5 从-2到1步长-3: " + lst5);
            WriteLine("1比2: " + lst1.CompareTo(lst2));
            WriteLine("3比4: " + lst3.CompareTo(lst4));
        }
    }