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Fibonacci series in Swift
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// Fibonacci series | |
// F[n] = F[n-1] + F[n-2] | |
// 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144 | |
// Find the fibonacci number for n interations | |
func fibonacci(n: Int) { | |
var num1 = 0 | |
var num2 = 1 | |
for _ in 0 ..< n { | |
let num = num1 + num2 | |
num1 = num2 | |
num2 = num | |
} | |
print("result = \(num2)") | |
} | |
fibonacci(7) | |
// Using Recursion | |
func fibonacciRecursiveNum1(num1: Int, num2: Int, steps: Int) { | |
if steps > 0 { | |
let newNum = num1 + num2 | |
fibonacciRecursiveNum1(num2, num2: newNum, steps: steps-1) | |
} | |
else { | |
print("result = \(num2)") | |
} | |
} | |
fibonacciRecursiveNum1(0, num2: 1, steps: 7) |
careful for future readers, this iterative solution is wrong. f(0) should return 0, f(1) = 1, f(2) = 1
func fibonacci(n: Int) { var num1 = 0 var num2 = 1 for _ in 0 ..< n { let num = num1 + num2 num1 = num2 num2 = num } print("result = \(num2)") } fibonacci(7)
THIS CODE IS WRONG
func fibonaccin (n: Int) -> Array{
assert (n > 1)
var array = [0,1]
while array.count < n {
array.append(array[array.count-1] + array[array.count-2])
print(array)
}
return array
}
fibonaccin(n: 5)
func fib(_ n: Int) -> Int {
guard n > 1 else { return n }
return fib(n-1) + fib(n-2)
}
for x in 0...10 {
print(fib(x))
}
Using decimal you can calculate to big number.
func fibonacci(n: Int) -> [Decimal] {
if n == 0 {
return [0]
}
if n == 1 {
return [0,1]
}
var sequence: [Decimal] = [0,1]
var num1: Decimal = 0
var num2: Decimal = 1
for _ in 2 ..< n+1 {
let num : Decimal = num1 + num2
num1 = num2
num2 = num
sequence.append(num)
}
return sequence
}
print("result = \(fibonacci(n: 120))")
This is being a bit clever:
/// Generates a series of `numberOfElements` many fibonacci element, using recursion.
func fibonnaci(numberOfElements n: UInt) -> [Int] {
let list = [0, 1]
guard n > 2 else {
return Array(list.prefix(Int(n)))
}
func inner(_ l: [Int]) -> [Int] {
let m = l.count
guard n != m else { return l }
return inner(l + [(l[m - 2] + l[m - 1])])
}
return inner(list)
}
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func fibonacci(n : Int){
var n1 = 0
var n2 = 1
}
fibonacci(n: 10)