Third Fibonacci Solution

fibonnaci_3.swift

/* Tercera Versión */
func fib3(n:UInt) -> UInt{
    if (n==0){
        return n
    }
    var last: UInt = 0
    var next: UInt = 1
    
    for _ in 1..<n{
        (last, next) = (next, last+next)
    }
    
    return next
}

fib3(n: 20)