C# 随机红包算法

static void Main(string[] args)
        {
            double totalAmount = 20;
            int num = 10;
            double minAmount = 0.01;
            Random r = new Random();
            for (int i = 1; i < num; i++)
            {
                double safeAmount = (totalAmount - (num - i) * minAmount) / (num - i);
                //double money = new Random().Next(Convert.ToInt32(minAmount * 100), Convert.ToInt32(safeAmount * 100)) / 100; 
                double money = NextDouble(r, minAmount * 100, safeAmount * 100) / 100;
                money = Math.Round(money, 2, MidpointRounding.AwayFromZero);
                totalAmount=totalAmount-money;
                totalAmount = Math.Round(totalAmount, 2, MidpointRounding.AwayFromZero);
                Console.WriteLine("第" + i + "个红包：" + money + " 元，余额：" + totalAmount + " 元");
            }
            Console.WriteLine("第" + num + "个红包：" + totalAmount + " 元，余额：0 元");

            Console.ReadKey();
        }

        /// <summary>
        /// 生成设置范围内的Double的随机数
        /// eg:_random.NextDouble(1.5, 2.5)
        /// </summary>
        /// <param name="random">Random</param>
        /// <param name="miniDouble">生成随机数的最大值</param>
        /// <param name="maxiDouble">生成随机数的最小值</param>
        /// <returns>当Random等于NULL的时候返回0;</returns>
        protected static double NextDouble(Random random, double miniDouble, double maxiDouble)
        {
            if (random != null)
            {
                return random.NextDouble() * (maxiDouble - miniDouble) + miniDouble;
            }
            else
            {
                return 0.0d;
            }
        }