递归算法转非递归算法 _阶乘

        /// <summary>
        /// 递归
        /// </summary>
        /// <param name="n"></param>
        /// <returns></returns>
        static int factorial(int n)
        {
            if (n > 1)
            {
                return factorial(n - 1);
            }
            else if (n == 1)
            {
                return 1;
            }
            return 0;
        }
        /// <summary>
        /// 非递归
        /// </summary>
        /// <param name="n"></param>
        /// <returns></returns>
        static int Factorial(int n)
        {
            Stack<Int32> st = new Stack<int>();
            st.Push(n);
            int tmp, total = 1;
            while ((tmp = st.Peek()) != 1)
            {
                total *= tmp;
                st.Pop();
                st.Push(tmp - 1);
            }
            return total;
        }
    }