fibonacci Algorithm
If the components being searched have non-uniform access memory storage (i. e., the time needed to access a storage location vary depending on the location accessed), the Fibonacci search may have the advantage over binary search in slightly reduce the average time needed to access a storage location.
On average, this leads to about 4 % more comparisons to be executed, but it has the advantage that one only needs addition and subtraction to calculate the index of the accessed array components, while classical binary search needs bit-shift, division or multiplication, operations that were less common at the time Fibonacci search was first published.
//An efficient way to calculate nth fibonacci number faster and simpler than O(nlogn) method of matrix exponentiation
//This works by using both recursion and dynamic programming.
//as 93rd fibonacci exceeds 19 digits, which cannot be stored in a single long long variable, we can only use it till 92nd fibonacci
//we can use it for 10000th fibonacci etc, if we implement bigintegers.
//This algorithm works with the fact that nth fibonacci can easily found if we have already found n/2th or (n+1)/2th fibonacci
//It is a property of fibonacci similar to matrix exponentiation.
#include <iostream>
#include <cstdio>
using namespace std;
const long long MAX = 93;
long long f[MAX] = {0};
long long fib(long long n)
{
if (n == 0)
return 0;
if (n == 1 || n == 2)
return (f[n] = 1);
if (f[n])
return f[n];
long long k = (n % 2 != 0) ? (n + 1) / 2 : n / 2;
f[n] = (n % 2 != 0) ? (fib(k) * fib(k) + fib(k - 1) * fib(k - 1))
: (2 * fib(k - 1) + fib(k)) * fib(k);
return f[n];
}
int main()
{
//Main Function
for (long long i = 1; i < 93; i++)
{
cout << i << " th fibonacci number is " << fib(i) << "\n";
}
return 0;
}
