[CTCI] Fobonacci Problem

The problem is well known, so there is no need to repeat it!

we can apply the iteration function f(n+1) = f(n)+f(n-1), however the time complexity is O(N).

We can reduce the time compexity to O(log(N)) using the method below.

f(1)=1,f(2)=1

$\begin{matrix}

f(n)&f(n-1)&\\

0& 0\\

\end{matrix}$