Fibonacci Series: #1 Most Common Coding Interview Question - Whiteboard Thursday 

I coded up an iterative algorithm before watching the video and here is what I came up with. It's a little bit of a different approach with the first two cases not being as easy to understand compared to just using an if(n

int Fib(int pos){ if (pos == 0) return 0; if (pos == 1) return 1; return Fib(pos - 1) + Fib(pos - 2); }

Perhaps begin the video with a description of the actual question... otherwise great video !

Great video, only thing what i observed is, It should return last+sLast , because fib(5) would be 8 but in your case it will return 5.

Great channel. Thank you Irfan. Your videos had been really useful to me. Knowing the algorithms is completely different from how you do them in white-boarding interviews. And that is what I've learned from your videos. Thank you.

With Binet's formula, it is much faster, although I wouldn't expect the candidate to come up with this during the interview. After all, we are programmers, not mathematicians. Nice video.

Assuming pos >= 0, then def fib(pos): if pos < 2 return pos values = [0, 1] val_pos = 1 for _ in range(pos - 2): val_pos = abs(val_pos - 1) values[val_pos] = values[0] + values[1] return values[pos]

def find_nth_fibb_num(n): if n

Sir i think this is the best solution to find number at position. int fibNumberAt(int pos) { int f1 = 0; int f2 = 1; int n = 0; while ( pos - - >1) { n = f1 + f2; f1 = f2; f2 = n; } return n; }

Int x=1,y=1,s=0,n; cin>>n; For(int i=0;i

Actually, you can solve this problem in O(log(n)) time using matrices and binary exponentiation ( I don't know us it necessary in interviews)

you can also get constant space, logarithmic time by using fast_expon for matrices. Note that the Fibonacci-recursion is given by [1,1;1,0]*[F_n;F_{n-1}]=[F_{n+1},F_n]. And now you just have to raise that matrix to the appropiate power.

here is my solution in c# public IEnumerable GetFibonacci(int number) { int prev = 1; int next = -1; for (int i = 0; i < number; i++) { int sum = prev + next; next = prev; prev = sum; yield return sum; } }

You are doing such a great job 👍👍

Hi Irfan, The explanation is in enough and complete. You should clearly and correctly explain.

Thank you for the clear explanations, can you pls also make series based on company like amazon, facebook etc.

Honestly, I do net get the recursive method. I mean that f[pos-1] +f[pos-2] implies that we know the numbers before pos, right? And how do we know them when nothing in the code above implies that we have calculated them already and saved them in the array. Can somebody elaborate on that? Thanks in advance

Can it be assumed that questions for whiteboard interviews would be simple, so that focus is on how you approach a problem?

Hi Irfan, Your videos are awesome! It would be nice if you provide task/condition on a separate slide at the beginning of a video.

Would this be the same concept when using maps --???

Hii man.. We both have same names !!! 😉

Good video, one thing though. I think you're returning the wrong value at the end. You are returning the "last" value, but you should be returning "last + secondLast" no?

Great videos!

I tweeted this

You need to explain it more clearly. The instructions quite a bit messed up. You need to define it more clearly

why wouldnt you use the golden ratio, would that be a bad answer at an interview

hey there, great stuff in ur videos. But the audio volume is low in your videos, please correct it, apart from that everything else is great. ! ! !

Probably include a link to the question? It's hard to follow your accent.