Calculate the Factorial of an Integer in C# 转

Calculate the Factorial of an Integer in C#

By , 18 Oct 2011
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Or you could just go the other direction and cache the known results ahead of time. You're only looking at 13 numbers in all, so it is not a big memory hog to just store those known values inside of the method and be done with it.
 

static uint Factorial(uint x)

{

  if (x > 12)

    throw new ArgumentException("Cannot calculate a factorial for numbers larger than 12");

  return _factorials[x];

}

static readonly uint[] _factorials = new uint[13] { 1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 39916800, 479001600 };

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