一. 生成随机数（可设定范围）

使用C#自带类System.Radom(int seed),来生成随机数，
使用Guid.NewGuid().GetHashCode(),生成新的Guid，然后获取它的Hash Code（int），作为种子放入System.Radom(int seed)使用。
种子作用是使每次生成的数字分布更加随机。
所有的随机数生成算法都是伪随机数。

二. 使用for循环，循环生成随机数，然后划分范围（概率分配），对落入不同范围内的随机数进行计数，最后计算出实际概率值。

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

namespace ConsoleApplication2
{
    class Program
    {
        static int randomNum;
        static int awards;
        static int a = 0;
        static int b = 0;
        static int c = 0;
        static int d = 0;
        static int e = 0;
        static int f = 0;
        static int g = 0;
        static int h = 0;
        static int ii = 0;
        static int j = 0;
        static int k = 0;
        static int l = 0;
        //添加整形变量为循环次数与概率分母，更改循环次数测试时，只要修改一个变量，即可得出正确概率
        static int Cnum = 10000;
        static void Main(string[] args)
        {   //循环次数更换为变量
            for (int i = 0; i < Cnum; i++)
            {

                string strprize = "";
                int payscore = 0;
                int itemid = 32;

                awards = new System.Random(Guid.NewGuid().GetHashCode()).Next(1, 1001);//抽奖概率随机数
                if (awards < 2) //1等奖
                {
                    strprize = "1等奖";
                    payscore = 100;
                    a = a + 1;

                }
                else if (awards < 6)
                {
                    strprize = "2等奖";
                    payscore = 50;
                    b = b + 1;
                }
                else if (awards < 11)
                {
                    strprize = "3等奖";
                    payscore = 40;
                    c = c + 1;

                }
                else if (awards < 51)
                {
                    strprize = "4等奖";
                    payscore = 20;
                    d = d + 1;

                }
                else if (awards < 125)
                {
                    strprize = "5等奖";
                    payscore = 5;

                    e = e + 1;
                }
                else if (awards < 201)
                {
                    strprize = "6等奖";
                    payscore = 1;
                    itemid = 46;

                    f = f + 1;
                }
                else
                {

                    randomNum = new System.Random(Guid.NewGuid().GetHashCode()).Next(1, 7);

                    if (randomNum == 1)
                    {
                        strprize = "7等奖";
                        payscore = 0;

                        g = g + 1;
                    }
                    else if (randomNum == 2)
                    {
                        strprize = "7等奖";
                        payscore = 1;
                        itemid = 46;

                        h = h + 1;
                    }
                    else if (randomNum == 3)
                    {
                        strprize = "7等奖";
                        payscore = 0;
                        ii = ii + 1;

                    }
                    else if (randomNum == 4)
                    {
                        strprize = "7等奖";
                        payscore = 10;
                        j = j + 1;


                    }
                    else if (randomNum == 5)
                    {
                        strprize = "7等奖";
                        payscore = 1;
                        itemid = 47;
                        j = j + 1;

                    }
                    else if (randomNum == 6)
                    {
                        strprize = "7等奖";
                        payscore = 1;
                        itemid = 47;

                        j = j + 1;
                    }
                }


            }
            //隐式转换时，要先把Cnum转换成double类型,然后除法的结果才能隐式转换为double
            double cnum = Convert.ToDouble(Cnum);

            Console.Write("1等奖:    " + (a / cnum).ToString("0.####%") +"    次数"+a+ "\n");
            Console.Write("2等奖:   " + (b / cnum).ToString("0.####%") + "    次数" + b + "\n");
            Console.Write("3等奖:   " + (c / cnum).ToString("0.####%") + "    次数" + c + "\n");
            Console.Write("4等奖:   " + (d / cnum).ToString("0.####%") + "    次数" + d + "\n");
            Console.Write("5等奖:    " + (e / cnum).ToString("0.####%") + "    次数" + e + "\n");
            Console.Write("6等奖:    " + (f / cnum).ToString("0.####%") + "    次数" + f + "\n");
            Console.Write("7等奖:    " + (g / cnum).ToString("0.####%") + "    次数" + g + "\n");
            Console.Write("7等奖:    " + (ii / cnum).ToString("0.####%") + "    次数" + ii + "\n");
            Console.Write("7等奖:   " + (h / cnum).ToString("0.####%") + "    次数" + h + "\n");
            Console.Write("7等奖:    " + (j / cnum).ToString("0.####%") + "    次数" + j + "\n");
            Console.ReadLine();
        }
    }
}