[Community Puzzle] Short accounts make long friends

Coding Games and Programming Challenges to Code Better

Send your feedback or ask for help here!

je n’ai trouvé aucun post sur ce puzzle, c’est pourquoi je crée celui-ci.
je bloque sur ce puzzle. Mon code est trop lent/long. Je combine tous les nombres avec toutes les opérations (méthode un peu brute-force). Je me doutais bien que cela allait coincer comme ça.
Quelqu’un peut-il m’indiquer une autre piste de résolution ?

I did not find any post on this puzzle, that is why I create this one.
I block on this puzzle. My code is too slow / long. I combine all the numbers with all the operations (a little brute-force method). I suspected that it would get stuck like this.
Can someone point me to another resolution lead?
Thank you.

1 Like

For any subset X of {a,b,c,d,e,f}, let S(X) be the set of all the values that can be reached using numbers from X. Find a way to compute S recursively – while memoizing the already computed values – to build an efficient enough dynamic programming approach.


It’s that kind of answer i was awaiting for. I don’t ask for “the” solution (no interest).
Thank you for this new approach. I’ll try it.
thanks again.

edit: but your approach also need to compute all that is possible from 6 numbers and 5 operators. Why should it be faster ?

@Zener Because with this approach you will structure the computation in such a way that you won’t do the same calculations too many times while, with your approach, one can guess that you’re doing the same calculations lots of times.

1 Like

I also have tried brute-force, and it took like 40 minutes to calc all possible equations.
@Niako, now I am going to rewrite my code according with your suggestion.

Ahh, finally submitted! Less then a quarter of second.
The hardest problem, and I’ve learned a lot. Thank you, @Niako!

1 Like

@MooMooN, all cases go through but i only get 83% when i submit my solution. I’ve been tested my code with many other combination of numbers and it always works. It blocks on validator 5. Do you have any idea why ?

Validator 5 has nothing special so I did the puzzle to see what could go wrong.

I partition a set s into 2 subsets and find the results recursively on each subset, so basically it looks like this:

for s1, s2 in partition(s):
_for a in results(s1):
__for b in results(s2):
___consider all possible results

I could reproduce your error when I don’t add a alone and b alone in all possible results