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  1. using System;
  2.  
  3. namespace Factorial
  4. {
  5.     class Program
  6.     {
  7.         static void Main(string[] args)
  8.         {
  9.             Factorial<intFact> f = new Factorial<intFact>(new intFact(5));
  10.             Console.WriteLine(f.Value);
  11.         }
  12.  
  13.     }
  14.  
  15.     struct intFact : IFactoriable<intFact>
  16.     {
  17.         public int n;
  18.         public intFact(int num)
  19.         {
  20.             n = num;
  21.         }
  22.         public bool isZero()
  23.         {
  24.             return n == 0;
  25.         }
  26.         public bool isBelowZero()
  27.         {
  28.             return n < 0;
  29.         }
  30.         public intFact Step()
  31.         {
  32.             return new intFact(n - 1);
  33.         }
  34.         public intFact Multiply(intFact iF)
  35.         {
  36.             return new intFact(n * iF.n);
  37.         }
  38.         public intFact getNeutralElement()
  39.         {
  40.             return new intFact(1);
  41.         }
  42.         public override string ToString()
  43.         {
  44.             return n.ToString();
  45.         }
  46.     }
  47.  
  48.     [Serializable]
  49.     class Factorial<T> where T : IFactoriable<T>
  50.     {
  51.         T p;
  52.  
  53.         public T Value
  54.         {
  55.             get;
  56.             private set;
  57.         }
  58.         public T Param
  59.         {
  60.             get 
  61.             { 
  62.                 return p; 
  63.             }
  64.             set 
  65.             {
  66.                 if (value.isBelowZero()) throw new ArgumentOutOfRangeException("n or Param");
  67.                 Value = fact(value); 
  68.                 p = value; 
  69.             }
  70.         }
  71.  
  72.         public Factorial(T n)
  73.         {
  74.             Param = n;
  75.         }
  76.  
  77.         T fact(T n)
  78.         {
  79.             if (n.isZero()) return n.getNeutralElement();
  80.             return n.Multiply(fact(n.Step()));
  81.         }
  82.     }
  83.  
  84.     interface IFactoriable<T>
  85.     {
  86.         bool isZero();
  87.         bool isBelowZero();
  88.         T Step();
  89.         T getNeutralElement();
  90.         T Multiply(T t);
  91.     }
  92. }
Success #stdin #stdout 0.03s 37032KB
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https://ideone.com/Dzefp
language:
C# (gmcs 5.20.1)
created:
12 years ago
visibility:
public

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