Edited to reduce the time taken to execute recursive for fibonacci

next_academy_solution_Recursion_vs._Iteration,_Benchmarking_It.rb

require 'benchmark'

def fibonacci_iterative(n)
  return 0 if n==0
  return 1 if n==1
  second_previous_num=0
  first_previous_num=1

  until n == 1
  	sum_of_two_num= first_previous_num + second_previous_num  #if n==2, sum_of_two_num=1  
  	second_previous_num=first_previous_num #if n==2, second_previous_num=1   
  	first_previous_num=sum_of_two_num #if n==2, first_previous_num=1 
  	n-=1
  end
  sum_of_two_num # return 1
end

Benchmark.bm {|x|  # benchmarking for iterative
  x.report{fibonacci_iterative(15)}
  x.report{fibonacci_iterative(20)}
  x.report{fibonacci_iterative(30)}
}


def fibonacci_recursive(n)
  return 0 if n == 0
  return 1 if n == 1
  fibonacci_recursive(n-1)+fibonacci_recursive(n-2)  
end

fibonacci_recursive_list=[10,100,1000]
Benchmark.bm {|x|  # benchmarking for recursive
  x.report{fibonacci_recursive(15)}
  x.report{fibonacci_recursive(20)}
  x.report{fibonacci_recursive(30)}
}