using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        double number = 3.54159;

        double roundedNumber = Math.Round(number); // 四舍五入到 2 位小数

        Console.WriteLine(roundedNumber); // 输出结果: 3.14

        ushort? fee = null;     

        Console.WriteLine((fee ?? 0) == 0 ? (ushort)0 : (ushort)((fee??0) - 4));

        // CalculateRebate();

    }

    private static void CalculateRebate()

    {

        sbyte PayWay = 9 , CardSettlementType = 0;

        ushort Fee = 38, FeeChannel = 23, FeeLevel1 = 23, FeeLevel2 = 23, FeeLevel3 = 25, FeeLevel4 = 0, FeeLevel5 = 0;

        long Amount = 13890, FeeAmount = Fee*Amount, FeeAmountChannel= FeeChannel * Amount;

        var totalFeeRegion = Fee - FeeChannel;

        var totalRebate = FeeAmount - FeeAmountChannel;

​

        if (totalFeeRegion == 0)

        {

            totalFeeRegion = 1;

        }

​

        if (PayWay == 12 && CardSettlementType == 1)

        {

            totalRebate = totalFeeRegion * Amount;

        }

​

        var feeDic = new List<KeyValuePair<int, int>>

        {

            new KeyValuePair<int, int>(0, FeeChannel),

            new KeyValuePair<int, int>(1, FeeLevel1),

            new KeyValuePair<int, int>(2, FeeLevel2),

            new KeyValuePair<int, int>(3, FeeLevel3),

            new KeyValuePair<int, int>(4, FeeLevel4),

            new KeyValuePair<int, int>(5, FeeLevel5),

        }.Where(w => w.Value != 0).OrderBy(o => o.Key).ToList();

        feeDic.Add(new KeyValuePair<int, int>(6, Fee));

​

        var rebateDic = new Dictionary<int, long>();

        Console.WriteLine($"feeDic.Count：{feeDic.Count}");

        for (int i = 0; i < feeDic.Count - 1; i++)

        {

            Console.WriteLine($"feeDic[i].Key：{feeDic[i].Key}，feeDic[i + 1].Value：{feeDic[i + 1].Value},i:{i}，feeDic[i].Value：{feeDic[i].Value}");

            rebateDic.Add(feeDic[i].Key, (long)Math.Round((double)(feeDic[i + 1].Value - feeDic[i].Value) * totalRebate / totalFeeRegion));

        }

​

        var RebateChannel = rebateDic.FirstOrDefault(f => f.Key == 0).Value;

        var RebateLevel1 = rebateDic.FirstOrDefault(f => f.Key == 1).Value;

        var RebateLevel2 = rebateDic.FirstOrDefault(f => f.Key == 2).Value;

        var RebateLevel3 = rebateDic.FirstOrDefault(f => f.Key == 3).Value;

        var RebateLevel4 = rebateDic.FirstOrDefault(f => f.Key == 4).Value;

        var RebateLevel5 = rebateDic.FirstOrDefault(f => f.Key == 5).Value;

        Console.WriteLine($"FeeAmount：{FeeAmount}，FeeAmountChannel：{FeeAmountChannel}");

        Console.WriteLine($"RebateChannel：{RebateChannel}，RebateLevel1：{RebateLevel1}，RebateLevel2：{RebateLevel2}，RebateLevel3：{RebateLevel3}，RebateLevel4：{RebateLevel4}，RebateLevel5：{RebateLevel5}");

    }

}