Fibonacci

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Fibonacci

The first two numbers in the Fibonacci sequence are 1 and 1. Every additional number in the sequence is the sum of the two previous numbers. The first six numbers of the Fibonacci sequence are 1, 1, 2, 3, 5 and 8.

Check for the fibonacci number

Write a getFib function that takes a number n as a parameter and returns the nth Fibonacci number. If n is zero, zero should be returned.

Sample Input and Output

Input: 4 Output: 3

Optimization

Try solving the problem using memoization and tabulation.

See:

https://indrabasak.wordpress.com/2016/04/03/exploring-fibonacci/

How much faster was the problem solved? How can you account for this in terms of time complexity? How about matrix exponentiation and fast doubling?

See:

https://www.nayuki.io/page/fast-fibonacci-algorithms

Write the getFib function
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function getFib (fibIndex) {