CODEWITHSUNDEEP
ruby
firesofhell
firesofhell

Reputation: 19

Why does my function outputting expected and unexpected values in ruby?

I have a method called fibs_rec that results in an unexpected output:

def fibs_rec(n)
  if n == 1 || n == 0 
    return 1 
  else 
    a = fibs_rec(n-1) + fibs_rec(n-2) 
    puts a
    return a 
  end 
end 

fibs_rec(5)

The call fibs_rec(5) should return 1,1,2,3,5 but here is the actual output:

2
3
2
5
2
3
8

Not only is the output incorrect, it lacks a number from the beginning.

Can someone explain why is this happening?

Upvotes: 0

Views: 47

Answers (1)

Vatsal Jain
Vatsal Jain

Reputation: 348

This is correct since your recursion is splitting into two sub-problems every time it recurses. If you want the series to appear properly then you should try doing this via dynamic programming for O(n) time complexity. As is, the first and second position won’t be printed because of the base case in the recursion.

As for the incorrect answer, it seems you have not accounted for the sequence starting with 0 index. Either find 4 index in the function which will give the fifth element or modify your function to work with position instead of index.

Upvotes: 1

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