自定义泛型类

class Stack<T>
    {
        private T[] items;
        private int idx;
        
        public Stack(int size)
        {
            items = new T[size];
            idx = 0;
        }
        public void Push(T x)
        {
            items[idx++]  = x; 
        }
        public T pop()
        {
            return items[--idx];
        }
    }