Project Euler Task 17

所以我目前正在处理Project Euler，我遇到了问题17。问题是

如果数字1到5是用单词写出来的：一、二、三、四、五，那么总共使用了3+3+5+4+4=19个字母。

如果从1到1000（包括1000）的所有数字都用单词写出来，会使用多少个字母？

就我个人而言，我认为问题会很直接。现在，我知道我的代码不是最优化的，我也知道我可以在网上找到解决方案。但我只是在寻找我的代码出了什么问题。我得到的答案是21224，而正确答案是21124。

  int Sum = 0;
    int Hundred;
    int Ten;
    int One;
    void Count()
    {
        for(int i = 0; i < 10; i++)
        {
            Hundred = i;
            for(int j = 0; j < 10; j++)
            {
                Ten = j;
                for(int k = 0; k < 10; k++)
                {
                    One = k;
                    switch(i)
                    {
                        case 0:
                            Tens();
                            break;
                        case 1:
                            Sum += 3;
                            Sum += 7;
                            Tens();
                            break;
                        case 2:
                            Sum += 3;
                            Sum += 7;
                            Tens();
                            break;
                        case 3:
                            Sum += 5;
                            Sum += 7;
                            Tens();
                            break;
                        case 4:
                            Sum += 4;
                            Sum += 7;
                            Tens();
                            break;
                        case 5:
                            Sum += 4;
                            Sum += 7;
                            Tens();
                            break;
                        case 6:
                            Sum += 3;
                            Sum += 7;
                            Tens();
                            break;
                        case 7:
                            Sum += 5;
                            Sum += 7;
                            Tens();
                            break;
                        case 8:
                            Sum += 5;
                            Sum += 7;
                            Tens();
                            break;
                        case 9:
                            Sum += 4;
                            Sum += 7;
                            Tens();
                            break;
                    }
                    
                }
            }
        }
        
        Sum += 11 + 99*9*3; //Taking into account the "one thousand" and the "and"s
        label1.Text = Sum.ToString();
    }
    void Tens()
    {
        switch (Ten)
        {
            case 0:
                Ones();
                break;
            case 1:
                switch (One)
                {
                    case 0:
                        Sum += 3;
                        
                        break;
                    case 1:
                        Sum += 6;
                        
                        break;
                    case 2:
                        Sum += 6;
                        
                        break;
                    case 3:
                        Sum += 8;
                        
                        break;
                    case 4:
                        Sum += 8;
                        
                        break;
                    case 5:
                        Sum += 7;
                        
                        break;
                    case 6:
                        Sum += 7;
                        
                        break;
                    case 7:
                        Sum += 9;
                        
                        break;
                    case 8:
                        Sum += 8;
                        
                        break;
                    case 9:
                        Sum += 8;
                        break;
                }
                break;
            case 2:
                Sum += 6;
                Ones();
                break;
            case 3:
                Sum += 6;
                Ones();
                break;
            case 4:
                Sum += 6;
                Ones();
                break;
            case 5:
                Sum += 5;
                Ones();
                break;
            case 6:
                Sum += 5;
                Ones();
                break;
            case 7:
                Sum += 7;
                Ones();
                break;
            case 8:
                Sum += 6;
                Ones();
                break;
            case 9:
                Sum += 6;
                Ones();
                break;
        }
    }
    
    void Ones()
    {
        switch(One)
        {
            case 0:
                
                break;
            case 1:
                Sum += 3;
                
                break;
            case 2:
                Sum += 3;
                
                break;
            case 3:
                Sum += 5;
                
                break;
            case 4:
                Sum += 4;
                
                break;
            case 5:
                Sum += 4;
                
                break;
            case 6:
                Sum += 3;
                
                break;
            case 7:
                Sum += 5;
                break;
            case 8:
                Sum += 5;
                
                break;
            case 9:
                Sum += 4;
                
                break;
        }
    }

 case 4:
     Sum += 6;
     Ones();
     break;

var onesDigit = new[] { 0, 3, 3, 5, 4, 4, 3, 5, 5, 4 };
var teens = new[] { 3, 6, 6, 8, 8, 7, 7, 9, 8, 8 };
var tensDigit = new[] { 0, 0, 6, 6, 5, 5, 5, 7, 6, 6 };