Fibonacci.swift

/*:
 # Wednesday Stretch Problem 6.3
 ## Fibbonacci Number
 
 ### Instructions:
 1. Create a function that finds the closest fibonacci number that is less than or equal to the number that is passed into a function.
 2. Don't hesitate to Google what a Fibonacci number is.
 3. Test it by passing in the number 2000. We will compare results.
 
 ### Black Diamond 💎💎💎
 Create the above using a single line of code in the function body. (Hint: recursion)
 */
import Foundation

func fibbonacci(under target: Int) -> Int {
    guard target > 0 else { return 0 }
    if target == 1 { return 1 }
    
    var a: Int = 0
    var b: Int = 1
    var sum: Int = 1
    
    while b < target {
        print("\(a) \(b)")
        a = b
        b = sum
        sum = a + b
    }
    
    return a
}

fibbonacci(under: 0) // 0
fibbonacci(under: 1) // 1
fibbonacci(under: 7) // 5
fibbonacci(under: 2000) // 1597