Re: [Haskell-beginners] Haskell Bin Tree Cellular Automata.

'iterate' uses optimization techniques, see the source code[0][1] (click the 'source' links). I didn't study these techniques in detail. [0] http://haddocks.fpcomplete.com/fp/7.8/20140916-162/base/Prelude.html#v:itera... [1] http://haddocks.fpcomplete.com/fp/7.8/20140916-162/base/GHC-Exts.html#v:buil... On Fri, 05 Jun 2015 01:31:07 +0200, Sourabh wrote:

Wow, it runs in 0.44 seconds now. This is incredible! Can you explain what just happened here?

On Thu, Jun 4, 2015 at 4:28 PM, Henk-Jan van Tuyl wrote:

...

On Fri, 05 Jun 2015 00:50:25 +0200, Sourabh wrote:

I figured out that I am constantly re-computing the trees, and decided to

...

try and memoize the results. Here is my memoization attempt:

https://github.com/cbrghostrider/Hacking/blob/master/HackerRank/FunctionalPr...

Basically I have changed the simulateCellularAutomata function, which computed the new trees, into a list (automataTrees - line 60). I was expecting the results to be memoized, but the runtime is unchanged.

At a glance: maybe if you change the line automataTrees starttree rule = (starttree) : [ simulateAutomataStep Nothing rule ((automataTrees starttree rule) !! (n-1)) | n <- [1..]] to automataTrees starttree rule = iterate (simulateAutomataStep Nothing rule) starttree it will run faster. The function 'iterate' can be found in Prelude and Data.List.

Regards, Henk-Jan van Tuyl

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