?12. Esli sushchestvuet tol'ko odin put' obhoda belogo regiona (ne petlya!) - ehto dast tol'ko odno ochko?

#12. If there is only one way to bypass the white region (not loop!) - this will give only one point?

Da, Vladimir, 1 ochko. Spasibo za otzyv! Zavtra uzhe mne predstoit serjozno potruditsja i proverit vse optimajzy.

Hi Riad,
A great contest, as usual.
Just to be sure :
- For 8 Rollball :do WE choose the first direction of the ball, or this direction must be forced by the location of 3 walls around its initial position ? (I mean : is it admitted that less than 3 walls are around the initial position of the ball?)
For 11-Opti-Rollerball : can the ball finish scratched against a wall ?

Hi Puzlifouk (your real name is hidden and I cannot use it in Contests):
8. Around the starting positions may not be walls.
11. The ball cannot stay with diagonal walls - in this case the ball needs to keep moving.

OK, Riad, thanks.
If you want to use it in a next contest, my first name is Nicolas :)
So for the 8, you confirm we choose the first direction of the ball, between saveral which are possible.

Yes, you must choose the first direction for the ball to roll.

Meh!! I had to enter my submission for #10 twice because of the two merged names in the initial version of the submission form & things didn't realign properly... but never checked that I forgot to enter 1 for Henna!!! Grrr... really annoying, esp. since it seems my solution was one of the optimal ones (105/561).

Anyway, it's my fault. But please, can we in the future avoid puzzles where submitting a solution is such a complicated process that requires filling a form with 140 entries in a user interface that was never meant for it? (esp. as, with Firefox on Linux at least, pressing Tab now moves forward by two form fields instead of one, so I keep skipping entries in LMI submission forms -- usually it's easy to spot a gap but in this case I guess it was above my double-checking abilities).

Denis

Happy to see I got an optimal solution for #10, but frustrated that I failed at entering my answer correctly (typo in one number)... I have to agree with auroux, it was hellish to answer this one and very hard to check.

About #11, I'm really interested in the methods solvers used to optimize it, as I have no idea on how to do it properly.

I have compassion, Denis and Anne (and others) but let's say that this problem was also a problem of checking technique: I spent a lot of time on this problem, because I wanted to be sure to get the best answer, and that it is valid: I hoped that the rule about the number of letters would be more discriminating ...

Puzzles:
1. Interesting puzzle. At some points I have to bifurcate for quite some time; I wonder what the logical path is.
2. Very nice, if on the easier side of puzzles.
3. Basically Pencilmark Sudoku. Not particularly interesting, but that's probably because I don't like Sudoku in general.
4. Surprisingly once I got the idea how to do these Build A Maze puzzles, this one falls pretty easily.
5. One of the more interesting puzzles I've had. There's that satisfying a-ha moment when the dice falls and I can finally make progress.
6. Not particularly interesting, either; when a Nansuke puzzle gets past a certain point, it becomes a chore to look through the numbers to find one of satisfying pattern. I just coded a little program to help me find numbers matching a pattern I want. Given that I have to check quite a lot of patterns, I'm not sure if some other solution can shortcut it a lot.
7. Didn't solve; haven't gotten the break-in yet.
8. Didn't solve for the same reason.
9. Very nice idea, actually; this is one puzzle I enjoyed a lot.
10. A very bad idea for a puzzle, because you can actually program it and get the answer in reasonable amount of time (read: 2 seconds), without needing to check all configurations. (When I submitted this, I forgot there's the tiebreaker, but it can still be solved using program even so.)
11. Also a poor idea because theoretically it can still be solved pretty quickly (read: polynomial-time), although this time it won't be so fast. Although that's just me being lazy to think; I'm sure there's a way to get a fast enough program to find the optimal solution.
12. One of my favorite optimizers. Got the right idea, but couldn't figure out how to get one line only. I predicted the winning score to be 1 or 2; apparently there are so many of them.

I put the points for puzzles 11 and 12.
I and Deb discussed the post of Denis. The April Contest participants can check the answers twice, not in a hurry. I will consider offers of Denis in the future.

Preliminary results were published. Max scored seven participants. I congratulate Christian, Dmitry, Ken, Stefano, Takuma, Tomoaki and Tomoya!

En réponse à Anne pour le #11 voici comment j'ai procédé : je trace tous les chemins possibles sans placer les marques, si possible avec des couleurs différentes pour bien les distinguer. Puis je marque toutes les intersections de ces différents chemins deux à deux. C'est a priori sur ces intersections qu'il va falloir placer les trois marques pour rabouter entre eux les chemins les plus longs. Bien sûr on regarde prioritairement les chemins les plus longs et on constate que les intersections se situent fréquemment vers le milieu, ce qui ne sera pas très intéressant car il faudra choisir une direction et l'on aura donc perdu la moitié de la longueur environ. Mais en y regardant de plus près on constate que deux des grandes chaînes possèdent une intersection quasiment à une de leur extrémité. Il n'y a alors plus qu'à regarder si les chemins qui en sont issus se recoupent, ce qui se vérifie et permet donc de positionner les trois marques . . .

Thanks Riad for this wonderful contest. I had a lot of fun as usual.
Could you please check something. I think I also have the max score of 99 points. In puzzle 10 I had 105 names and 561 letters, but I received no points.

i couldnt see what is wrong in my solution below,







Attachments
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q1.png (21KB - 1 downloads)

@duran :
in the green corner at the bottom on the right, there are more X than O...

You're right Hugo, we have eight winners and you're one of them, sincerely congratulations!