program.cs

本程序实现了4的一万次方。欢迎大家来查看。

using System;
using System.Collections;
using System.Diagnostics;

namespace IBMS.Algorithem
{
    /// <summary>
    /// N2Class
    /// </summary>
    class N2
    {
        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main(string[] args)
        {
            N2 newObject = new N2();

            int baseNum = 4;
            int testN = 10000;

            Console.WriteLine("Std Math Lib Caculating result:" + Math.Pow(baseNum, testN).ToString());
            Console.WriteLine("Wait...now begin to caculate..");

            int[] result = newObject.Power(baseNum, testN);

            Console.WriteLine("Caculate Result:");

            for (int i = result.Length - 1; i >= 0; i--)
            {
                Console.Write(result[i]);
            }

            Console.WriteLine("");
        }

        int[] Power(int baseNum, int n)
        {

            int[] result;

            if (n < 0)
            {

                throw new Exception("现在还不支持负指数");
            }
            if (n == 0)
            {
                result = new int[1];
                result[0] = 1;
                return result;
            }

            //获得结果位数
            int size = (int)(n * Math.Log10(baseNum)) + 1;

            result = new int[size];
            result[0] = 1;

            for (int i = 0; i < n; i++)
            {
                Multi_Vector(result, baseNum);
                //Console.WriteLine("Caculate {0}'s {1} ",baseNum,i+1);
            }

            return result;
        }

        void CheckCarray(int[] m, int index)
        {

            if (m[index] >= 10)
            {
                //向高位进位，模拟手算
                m[index + 1] += m[index] / 10;

                //设置当前位
                m[index] %= 10;

                //检查下一个位时候需要进位
                CheckCarray(m, index + 1);
            }
        }


        /// <summary>
        /// 矢量和一个整数的乘法运算
        /// </summary>
        /// <param name="m">矢量</param>
        /// <param name="n">乘数</param>
        void Multi_Vector(int[] m, int n)
        {
            int totalBit = 0;

            for (int i = m.Length - 1; i >= 0; i--)
            {
                if (m[i] > 0)
                {
                    totalBit = i + 1; //获得最高位
                    break;
                }
            }

            Debug.Assert(totalBit != 0);

            for (int i = totalBit - 1; i >= 0; i--)
            {
                //从高位到低位开始算
                int temp = m[i] * n;
                //产生一个进位
                if (temp >= 10)
                {
                    //向高位进位，模拟手算
                    m[i + 1] += temp / 10;
                    //检查该位是否还需要进位
                    CheckCarray(m, i + 1);
                    temp %= 10;
                }
                m[i] = temp;
            }
        }
    }
}