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Now we're coming to some really hilarious questions, because this stuff you will never use in your

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everyday life like a programmer, but you must know how to solve it.

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And the first one here, which is my favorite design, the function which returns a Fibonacci sequence

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value and they didn't write the function to get the Fibonacci value in the last 12 years, which actually

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means it is not that needed.

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But I am constantly hear this question again and again on the interview.

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And actually, I think that it is totally fine to ask the interviewer, OK, I don't know, a formula

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for Fibonacci.

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Can you please say it and then they can code it?

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It's not a problem.

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And this is totally fine, because you should not know by heart.

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All mathematical formulas.

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This is what here.

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Actually, you can get something like this as a result for your question.

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So here you can see that Fibonacci sequence is an integer sequence where the first two terms is zero

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and one after the next term is defined as a sum of previous two terms.

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And the else term is the sum of and minus one and and minus two, which actually means this is a typical

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start of the sequence we have here zero, one, one and two.

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And as you can see here, we can sum, for example, one and one, and we get into here with some one

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and two and we get them three and so on and so on.

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So how we can solve this, we must provide in our function a Fibonacci sequence value, which actually

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means the index in this sequence.

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For example, if we will provide seven as an argument, then we must get here 21.

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Because actually we will sum up eight and 13 and we're getting 21.

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Now let's call this exercise and actually he'll be able to use recursion because if you want to calculate

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its recursive loop.

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So here we can create a Fibonacci function and we get here and which is our index.

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And here, first of all, we must check if it is less than two, because in this case, our logic won't

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work because here we have zero and one.

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This is we have a master, OK, if and less than two, then he'll want to return one.

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In other cases, we must apply our logic.

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And here we simplify return Fibonacci.

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And here we are passing and minus two, which actually means we calculate this function recursively.

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And every single recursive call of Fibonacci will call it again and again until we will come to this

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first condition.

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So here we have Fibonacci and minus two plus Fibonacci and minus one.

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And actually, this is a whole code that you must trade.

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Let's check this out.

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I will just jump in the console and right here, Fibonacci seven.

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And as you can see, we're getting 21, which actually means our code is working.

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But here are some important stuff to remember.

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As a programmer, you must know how to convert mathematical formulas or some logic in JavaScript functions

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or functions in any other language, but it's totally fine to not know beyond all mathematical formulas.

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This is why you should not afraid to ask about them.

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And secondly, I think it is totally fine to ask in return.

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OK, I can't feel the code it, but are you using this stuff every single day in your project?

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And probably you will get an answer.

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No.

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This is why actually, it doesn't make any sense to ask this stuff in the first place.