需要要一个金额递减的效果，最终的效果如下，这其实就是一个等差数列。
我们学过的等差数列求和公式是：
也就是首末相加乘以N再除以2.而我们得到的参数是总金额和总人数，求整个数列。我们默认最小的差值是0.01，也就是一分钱，首项是a0,那么aN=a0+(n-1)*gap代码如下：
private decimal[] GetDeclines(decimal reward, int people, decimal min) { //需要验证min 和 gap //min不能大于平均值。gap可以是0， //求和公式 2*reward=(a0+ak)*n k=n-1 //people只有一人 if (people == 1) return new[] { reward }; //min等于平均值 if (min == (reward / people) && ((int)reward * 100 % people == 0)) return GetAverages(reward, people); var a_0a_n = 2 * reward / people;//得到首末两项的和 var gap_n_1 = a_0a_n - 2 * min;//得到peple-1个间距的值 var gap100 = (int)(gap_n_1 / (people - 1) * 100);//放大一百倍 确保小数 var gap = (decimal)gap100 / 100; var results = new decimal[people]; //然后逐个求出每一项的值。 for (int i = 0; i < people; i++) { results[i] = min + gap * (people - i - 1); } var sum = people * (results[0] + results[people - 1]) / 2; var more = reward - sum; results[0] = results[0] + more; return results; }
关键是通过min计算出差额gap，而这个差值我们可以默认的设置为总金额的五十分之一。
if (model.Reward >=1) { model.MinReward = model.Reward / 50; }
金额不可能每次被完全分掉，这里是将多出的金额加到了的第一项里面。
你会发现剩余金额其实不会随着总金额变大而变大，居然是一样的。有点意思。console代码如下：
class Program { static void Main(string[] args) { GetDeclines(1000, 10); Console.Read(); } private static decimal[] GetDeclines(decimal reward, int people) { var min=(decimal)0.01; if (reward > 1) { min = reward/50; } //需要验证min 和 gap //min不能大于平均值。gap可以是0， //求和公式 2*reward=(a0+ak)*n k=n-1 //people只有一人 if (people == 1) return new[] { reward }; //min等于平均值 if (min == (reward / people) && ((int)reward * 100 % people == 0)) return GetAverages(reward, people); var a_0a_n = 2 * reward / people; var gap_n_1 = a_0a_n - 2 * min; var gap100 = (int)(gap_n_1 / (people - 1) * 100); var gap = (decimal)gap100 / 100; var results = new decimal[people]; Console.WriteLine("总金额{0},最小值{1},{2}个人,差额{3}", reward, min, people,gap); for (int i = 0; i < people; i++) { results[i] = min + gap * (people - i - 1); Console.WriteLine("第{0}项：{1}",i,results[i]); } var sum = people * (results[0] + results[people - 1]) / 2; var more = reward - sum; Console.WriteLine("剩余"+more); results[0] = results[0] + more; return results; } private static decimal[] GetAverages(decimal reward, int people) { var per = reward / people; var ds = new decimal[people]; for (int i = 0; i < people; i++) { ds[i] = per; } return ds; } }
原文：http://www.cnblogs.com/stoneniqiu/p/6308923.html
