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  1. using System;
  2.  
  3. class Program
  4. {
  5.     static void Main(string[] args)
  6.     {
  7.         var rnd = new Random();
  8.         for (int i = 0; i < 10; i++)
  9.         {
  10.             int x = rnd.Next(10000);
  11.             string encoded = AbcNotation.Encode(x);
  12.             int decoded = AbcNotation.Decode(encoded);
  13.             Console.WriteLine("{0} -> {1} -> {2}", x, encoded, decoded);
  14.         }
  15.     }
  16. }
  17.  
  18. public static class AbcNotation
  19. {
  20.     public const int AlphabetsCount = 26;
  21.  
  22.     // A -> 1, AA -> 27, AAA -> 703, .....
  23.     private static int DecodeRepeatedA(int digits)
  24.     {
  25.         return digits == 1 ? 1 : (int)Math.Pow(26, digits - 1) + DecodeRepeatedA(digits - 1);
  26.     }
  27.  
  28.     // decode "ABC" as simple 26-adic encoded.
  29.     private static int DecodeAs26Adic(string se)
  30.     {
  31.         int msd = AtoI(se[0]);
  32.         int power = (int)Math.Pow(AlphabetsCount, se.Length - 1);
  33.         return se.Length == 1 ? msd : msd * power + DecodeAs26Adic(se.Substring(1));
  34.     }
  35.  
  36.     public static int Decode(string abc)
  37.     {
  38.         return DecodeRepeatedA(abc.Length) + DecodeAs26Adic(abc);
  39.     }
  40.  
  41.     // Encode to Simple 26-adic notaion using A to Z.
  42.     private static string EncodeAs26Adic(int x, int digits)
  43.     {
  44.         int power = (int)Math.Pow(AlphabetsCount, digits - 1);
  45.         int msd = x / power;
  46.         int remainder = x - power * msd;
  47.  
  48.         return digits == 1 ? ItoA(x).ToString() : ItoA(msd) + EncodeAs26Adic(remainder, digits - 1);
  49.     }
  50.  
  51.     public static string Encode(int x)
  52.     {
  53.         int digits = GetEncodedLength(x);
  54.         return EncodeAs26Adic(x - DecodeRepeatedA(digits), digits);
  55.     }
  56.  
  57.     // Return length of ABC encoded string.
  58.     private static int GetEncodedLength(int x)
  59.     {
  60.         for (int i = 2; ; i++) if (x < DecodeRepeatedA(i)) return i - 1;
  61.     }
  62.  
  63.     private static int AtoI(char c)
  64.     {
  65.         return c - 'A';
  66.     }
  67.  
  68.     private static char ItoA(int figure)
  69.     {
  70.         return (char)('A' + figure);
  71.     }
  72.  
  73. }
  74.  
Success #stdin #stdout 0.04s 24216KB
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stdin
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Standard input is empty
stdout
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4836 -> GCZ -> 4836
4264 -> FGZ -> 4264
6071 -> HYM -> 6071
5955 -> HUA -> 5955
1953 -> BWC -> 1953
4601 -> FTY -> 4601
6483 -> IOI -> 6483
2605 -> CVE -> 2605
699 -> ZW -> 699
3605 -> EHQ -> 3605
https://ideone.com/RswjZk
language:
C# (gmcs 5.20.1)
created:
9 years ago
visibility:
public

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