Get reverse of a list inside the function that returns the list

Question

So I have to get the elements under odd indices in reverse.

I have written a function to get me odd index elements but I am not sure how to make them return in reverse.

I have to do this in one function and it has to be recursive.

Could you please show your code? What did you try? Which programming language are you going to use? — abarisone, Apr 08 '15 at 06:17

score 0 · Accepted Answer · answered Apr 08 '15 at 07:14

0

What you're doing is taking the first element then append the rest of result. If you do it other way around, then you'd get the reversed list. Thus, You can get the reverse list simply swapping the append's arguments.

NOTE: The code costs O(n^2) and consumes stack for each recursive call. So it's better to make it tail recursive, then the Scheme implementation you're using optimises it not to consume stack.

answered Apr 08 '15 at 07:14

Takashi Kato

646
3
5

I just figured it out earlier and used the same solution you mentioned here! Thanks for your help. Could you please go a little into detail on Tail Recursion? Maybe with code hints? – Ashleyy Apr 08 '15 at 07:40
1

http://stackoverflow.com/questions/310974/what-is-tail-call-optimization this question has all the answers :) – Christophe De Troyer Apr 08 '15 at 09:02

Get reverse of a list inside the function that returns the list

1 Answers1