# [plt-scheme] Re: HTDP Exercise 12.4.2 ... Help! (Solved!!)

I admire your persistence ; I became so discouraged that i haven't
looked at
htdp since early april; So i have to pick myself up and get back to
it.
mike
On May 2, 7:34 pm, S Brown <ontheh... at gmail.com> wrote:
>* I just wanted to update this topic in order to say that I have finally
*>* solved this exercise the *correct* way! Thank you very much to
*>* everyone here who provided input.
*>*
*>* For anyone who finds this topic and is looking for help with this
*>* exercise:
*>*
*>* 1. Learn the right way to think about recursion. Don't make the
*>* mistake I made and try to put the entire recursive process into your
*>* head all at once. It simply doesn't work. Even writing down all of the
*>* results of the recursion step-by-step won't help. Instead, use the
*>* definition of the function itself to understand how the recursion
*>* works, and then create the rest of the function as if the recursive
*>* call already does what it's supposed to do.
*>*
*>* 2. Follow the design recipes. This exercise is probably the first one
*>* in the book where you pretty much have to use the design recipes in
*>* order to find the right solution. The specific recipe you should be
*>* looking at here is in section 9.4
*>*
*>* 3. Walk away from this exercise if/when you get frustrated. Take a
*>* walk, watch a movie, etc. Basically, go do something that doesn't
*>* require a lot of thinking.
*>*
*>* 4. Don't give up on it until you have the solution. It's worth it once
*>* you solve it because you gain a better understanding of how to use and
*>* think about recursion, and how to use the design recipes.
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