C#实现微信红包功能

class Program
 {
  static void Main(string[] args)
  {
   //初始化要发起的红包基础数据
   double total = 100;
   int num = 50;
   double min = 0.01;
   string temp;
   bool flag = false;
   Console.WriteLine(string.Format("是否需要自定义红包金额和数量（默认{0}元/{1}人）Y/N：", total, num));
   temp = Console.ReadLine();
   if (temp.Trim().ToLower().Equals("y") || temp.Trim().ToLower().Equals("yes"))
   {
    Console.WriteLine("请输入你要发起的红包金额：");
    do
    {
     temp = Console.ReadLine();
     flag = double.TryParse(temp, out total);
     if (!flag)
     {
      Console.WriteLine("金额必须为整数或小数，请重新输入：");
     }
    } while (!flag);
    Console.WriteLine("请输入你要发起的红包个数：");
    do
    {
     temp = Console.ReadLine();
     flag = int.TryParse(temp, out num);
     if (!flag)
     {
      Console.WriteLine("红包个数必须为整数，请重新输入：");
     }
    } while (!flag);
   }

   total -= min * num;
   if (total < 0)
   {
    Console.WriteLine("抱歉，你的金额不足！");
    return;
   }

   //产生正态分布的随机红包金额，并计算相关的金额和数量保证数据的准确性
   double average = total / num;
   double variance = 1;
   Random u1 = new Random();
   Random u2 = new Random();
   double[] nums = new double[num];

   for (int i = 0; i < num; i++)
   {
    double? result = total;
    if (i < num - 1 && total > 0)
    {
     do
     {
      result = Round((double)Normal(u1.NextDouble(), u2.NextDouble(), average, variance), 2);
     } while (result == null || result < 0);
     if (total > result)
     {
      total = (double)Round((total - (double)result), 2);
     }
     else
     {
      result = total;
      total = 0;
     }
    }
    else if (i == num - 1)
    {
     total = 0;
    }
    nums[i] = Math.Round(min + (double)result, 2); //浮点运算问题，这里需要四舍五入数据才正确

    Console.WriteLine(string.Format("第{0}个红包金额：{1}", i + 1, (min + result)));
    Console.WriteLine("剩余金额：" + ((i != num - 1 && total == 0) ? min * (num - i - 1) : total + (min * (num - i - 1))));
   }
   Console.WriteLine("最大金额：" + nums.Max());
   Console.WriteLine("最小金额：" + nums.Min());
   Console.WriteLine("总额：" + Round(nums.Sum(), 2));
   Console.WriteLine("初始方差：" + variance);
   Console.WriteLine("结果方差：" + Variance(nums));
   Console.WriteLine("按任意键退出！");

   Console.ReadKey();
  }

  /// <summary>
  /// 产生符合正态分布的随机数
  /// </summary>
  /// <param name="u1">正态分布第一个随机数</param>
  /// <param name="u2">正态分布第二个随机数</param>
  /// <param name="averageValue">正态期望(平均值)</param>
  /// <param name="variance">正态标准差(Math.Sqrt(方差))</param>
  /// <returns></returns>
  public static double? Normal(double u1, double u2, double averageValue, double variance)
  {
   double? result = null;
   try
   {
    result = averageValue + Math.Sqrt(variance) * Math.Sqrt((-2) * Math.Log(u1)) * Math.Sin(2 * Math.PI * u2);
   }
   catch (Exception)
   {
    result = null;
   }

   return result;
  }

  /// <summary>
  /// 求一组数据的方差
  /// </summary>
  /// <param name="list">要求的数组</param>
  /// <returns></returns>
  public static double Variance(double[] nums)
  {
   double average = nums.Sum() / nums.Length;
   double sum = 0;
   double variance = 0;
   foreach (double num in nums)
   {
    sum += Math.Pow((num - average), 2);
   }
   variance = sum / nums.Length;

   return variance;
  }

  /// <summary>
  /// 截取小数指定小数位，且不四舍五入
  /// </summary>
  /// <param name="originNum">要截取的小数</param>
  /// <param name="lastNum">截取小数后位数</param>
  /// <returns></returns>
  public static double? Round(double originNum, int lastNum)
  {
   double? result = null;
   int index = originNum.ToString().IndexOf('.');
   if (index != -1)
   {
    string temp = originNum.ToString();
    result = Convert.ToDouble(temp.Substring(0, index + 1) + temp.Substring(index + 1, Math.Min(temp.Length - index - 1, lastNum)));
   }
   if (result == 0)
   {
    result = null;
   }
   else if (index == -1)
   {
    result = originNum;
   }

   return result;
  }
 }