Evaluate binomial coefficients: Difference between revisions

=={{header|Swift}}==

<lang swift>func factorial<T: BinaryInteger>(_ n: T) -> T {

guard n != 0 else {

return 1

}

return stride(from: n, to: 0, by: -1).reduce(1, *)

}

func binomial<T: BinaryInteger>(_ x: (n: T, k: T)) -> T {

let nFac = factorial(x.n)

let kFac = factorial(x.k)

return nFac / (factorial(x.n - x.k) * kFac)

}

print("binomial(\(5), \(3)) = \(binomial((5, 3)))")

print("binomial(\(20), \(11)) = \(binomial((20, 11)))")</lang>

{{out}}

<pre>binomial(5, 3) = 10

binomial(20, 11) = 167960</pre>