Swift Fun Algorithms #6: Fibonacci Sequence

[@coderlife200]

Hi Brian,
Great tutorials you showing us. For fibonacci, i've included one boolean parameter indicating for the first step to include [0,1]
func fibRecursiveFor(numSteps: Int, first: Int, second: Int, firstStep: Bool) -> [Int]{
if numSteps == 0 {
return []
}
if firstStep {
return [0,1] + [first + second] + fibRecursiveFor(numSteps: numSteps - 1, first: second, second: first + second, firstStep: false)
}
return [first + second] + fibRecursiveFor(numSteps: numSteps - 1, first: second, second: first + second, firstStep: false)
}
fibRecursiveFor(numSteps: 9, first: 0, second: 1, firstStep: true)

[@richardgmartinonline]

Hi Brian: I think your recursive technique is offset by one index. When you call with numSteps as '5', it should return [0, 1, 1, 2, 3, 5], instead it returns [0, 1, 1, 2, 3, 5, 8] - which is an index, or numStep, of 6.

[@LetsBuildThatApp]

+Richard Martin good catch, as long as you understand the algorithm you’re good

[@desmondbraxton6387]

Good video, it explains alot. Do you think I can use this for the running sum leetcode problem?

[@krutomjer]

I love it how you're secretly smiling while writing the recursive function :D

[@Simran95100]

could you please add more videos relating algorithm..as these are also quite helpful thanks

[@LetsBuildThatApp]

Hi Simran, I think I ran out of ideas for algorithms so I stopped...

[@quickfingers5982]

Lets Build That App more algorithms please!

[@jelly1928]

@@LetsBuildThatApp dynamic programming

[@MAX-uh6kh]

hey, is the a way to do this with only var and print?

[@eduardovanin9824]

Lol, I've been studying swift for two months and when I see you doing things like these so fast, and explaining it I just get like
hell yeah, he is so good
hopefully ur doing good, lets keep up the good work!

[@ahmedmohna1986]

Its prepared lesson bro , no one can think in this fast, dont think like this way and compare yourself with him u will frustrate

[@Brofehst]

Hey man! Great video - I really like your video setup. What are you using to record yourself / your screen at the same time? Are you using anything in particular for editing? Thanks!

[@wdw5000]

Noticed your videos are mostly algorithm based now. Will you be recreating any apps in the near future?

[@LetsBuildThatApp]

+wdw5000 Yes, I just got back from an 8 day Taiwan vacation and getting back into the groove of things. Currently working on producing how to create UA-cam app series but takes time as you can imagine. These algorithm videos are here to satisfy your hunger for now :)

[@superwsuperw]

How was your Taiwan vacation?

[@LetsBuildThatApp]

Taiwan is really awesome, I enjoyed staying in Taipei, yilan, and hualien. Being able to travel to all these places without a car was real nice.

[@jasonbakthakumar3533]

Please make a video on String algorithms in Swift.. It'll be really great....

[@ahmedmohna1986]

Theres wrong with shorter way its give one more noumber , you should make numsteps-2

[@jameshe754]

Cannot use mutating member on immutable value: 'fibForNumbers' returns immutable value
anyone know why?
when I use return fibForNumbers(numberOfSteps: numberOfSteps-1).append(fibNumber(number: numberOfSteps))
.instead when I use return fibForNumbers(numberOfSteps: numberOfSteps-1) + [fibNumber(number: numberOfSteps)] is fine
any now knows the difference between append a element to an army and just + one
func fibForNumbers (numberOfSteps: Int) -> [Int]{
// if numberOfSteps Int{
if number == 1{
return 0
}
else if number == 2{
return 1
}
else{
return fibNumber(number: number-1) + fibNumber(number: number - 2)
}
}
fibNumber(number: 5)
fibForNumbers(numberOfSteps: 5)

[@killerwolf1983]

thank yo, but there is a simpler solution: func fib(_ n: Int) -> Int {
guard n > 1 else {return n}
return fib(n - 1) + fib(n - 2)
}

[@nikitatroin]

simpler, но с n = 100, он будет выполнять эту функцию 50 000 лет

[@JasonMitchellAZ]

Good stuff!

[@elielimelech5151]

Very good and helpful 👌

[@scollaco1027]

Hey man, I really like your algorithm videos, but read below that you ran out of ideas. So what you think of making videos based on the "swift algorithm club" (github.com/raywenderlich/swift-algorithm-club)? Just a suggestion :)

[@LetsBuildThatApp]

+Saturnino collaço I'm actually an android author on rays website, I'm not going to encroach on their content :)

[@taylormaxwell1277]

Thanks you, very helpful

[@PythonPlusPlus]

I don't like the way you did the recursive function, it's not very intuitive. Here's my version:
func recursiveFib(for numSteps: Int) -> [Int] {
if numSteps < 0 {
return []
}
if numSteps < 2 {
return [Int](0...numSteps)
}
let previous = recursiveFib(for: numSteps - 1)
return previous + [previous[numSteps - 2] + previous[numSteps - 1]]
}

[@LetsBuildThatApp]

Good job. I think there are many different solutions to this problem, good that you found one that suits your coding preference.

[@falsanomo]

I like this because it's all self-contained within the function. The function runs beautifully without the first if-statement so I'm not sure why that was added. Edit: Oh, I see the if-statement is used to handle negatives. :)