looking forward to this

Confused -- the timer on the page now says it starts in 49 days ???

Sorry about that, corrected now.

believe there is a typo in puzzle 9. the text says the ships are 10 but the figure shows 15. please clarify

Hi Stefano, 15 ships as shown, thank you for the clarification!

The only sudoku is named nonsudoku !!!

The charm of the English translation
Perhaps we should use a hyphen. But the name was approved in preparation for the September Sudoku Contest.

Sorry but the instructions of puzzle 11 OPTI BALL are unclear to me. Getting old. Need help.
I notice the puzzle is similar to puzzle 8 and perhaps this may induce misunderstanding.
first question.The instructions say that I can put up to 3 right angled triangles in any cell except the start. I can see how to put ONE triangle. I can see how to put TWO triangles (for example A and D) turning a white cell into a black one. But I cannot see how I can put 3 triangles. please explain
Second question: can the ball conclude its route leaving the grid, as in puzzle 8? Or it must stay within the grid at all time, and can only conclude its path against a wall (similar to Tiger in the wood)? Are both options possible?
Third question: What do you mean with the sentence "The ball cannot return back"? I assume the path of the ball can cross itself in an empty white square as in the puzzle 8, and this sentence is not forbidding this, please confirm

Can I submit an answer twice or more if I find an error in a solution?

You can submit as many times as you want. We will consider only the final submission. Also, there is no penalty for wrong submissions.

Excellent timing, just right to keep me busy over the 4-day weekend here. :)

There is an error in the answer page for puzzle 10. Two names (LAM/LAURA) share he same box

1. I showed might look like the answer. It implies that the 3 triangles do not need to put in one cell. The triangles in the example were in cells H1, H0, K3.
2. Both are possible. This is the only difference between the puzzle 8 and 11.
3. The ball can cross any cell twice, but could not bounce back 180 degrees from a fully black square, that is, the path cannot overlap itself.

Fixed. Please refresh the submission page.

I said I am getting old......

Edited by forcolin 2017-04-12 8:07 PM

With reference to puzzle 12: how much is the score of a line of cell with a unique path but not forming a loop? (for example a group of 3 cells)

1 mark.
You remind me a hit of Deep Purple, which I played the guitar: "But I feel I'm growing older..."

"And the songs that I have sung..."

Hi Riad, some 'easy' questions (just to clarify):
11 OPTI-ROLLBALL: We can place a maximum of 3 triangles in the grid?
11 OPTI-ROLLBALL: The path cannot repeat in an infinite loop, so "M14W" is not allowed?
11 OPTI-ROLLBALL: You can enter the start cell again (at 90 degrees), so "K17Z" is 11.5 points?
12 PENTOMINOES AND LINES: We must place all 12 pentominoes in the grid (so placing only 11 is not valid)?
12 PENTOMINOES AND LINES: In every white region, it is possible to visit every cell with a single line. So a white region in the shape of a T-pentomino is not valid?
12 PENTOMINOES AND LINES: If a region has 2 possible loops (e.g. a white 4x3 rectangle), then it gets 'many many' points?

Hi James,
11. You can place a maximum of 3 triangles in the grid, but may be less, such as 2, 1 or 0.
The path cannot repeat in an infinite loop (“echo in the distance” will not help).
The start cell can be crossed again (at 90 degrees).
12. You must place all 12 pentominoes in the grid.
In every white region, it is possible to visit every cell with a single line. A white region in the shape of a T-pentomino is not valid.
If a region has 2 possible loops (e.g. a white 4x3 rectangle), then it gets 2 points. I should have been clearer to say about it in the text.

Argh. The goal in 12 is to *minimize* the total score!! Just spent many hours trying to maximize it...

To clarify about 12: if there is a loop passing through all cells in a region, the number of marks (or rather, penalty points) you get from that region is equal to the number of loops you have there; otherwise, it's the number of lines?

Edit: More questions.

For 10, the tiebreaker is the total number of letters used in all names?

For 7, a match head catches fire if any of the other cells sharing a side to it also catches fire?

For 5, half-dominoes may not occupy black cells even if the part covering the black cells are empty (no circles)?

Edited by chaotic_iak 2017-04-13 8:36 PM

12. Yes, number of loops/lines.
10. Maximize the number of names, using the least possible letters.
7. The head of the match lit from the flame in an adjacent cell (sharing a side).
5. The black cell should not be on half-domino.

It has been so much time to not attempt to solve Riad's puzzles. Yesterday I solved nine of them and I had quite fun. Thanks Riad, really I missed your style.

Thank you Serkan, I am very pleased and I'm glad to see you among the participants of April Contest!

For info. IUPAC has recently annouced the names (and symbols) of 4 new elements.

Nihonium and symbol Nh, for the element 113,
Moscovium and symbol Mc, for the element 115,
Tennessine and symbol Ts, for the element 117, and
Oganesson and symbol Og, for the element 118.

the new complete periodic table is available from [url] https://www.iupac.org/cms/wp-content/uploads/2015/07/IUPAC_Periodic_... [/url]

May be useful for the next contest.


Edited by forcolin 2017-04-14 8:46 PM

For #4 (build a circular maze), which direction are the digits going? Are they read outside to inside?

Also for #9 (Fleet between the pentominoes), how does the answer key work? It says "- or + or FILNPSTUVWXY" -- is "-" for no ship and "+" for ship and the letters for pentominoes?

Also I think there is a typo? J isn't a pentomino but N is. Or is that a different naming system?

Edited by mstang 2017-04-17 3:24 AM

J is used in this contest.

They are read outside to inside.

Congratulations Riad. Excellent puzzles. Great fun!

Thank you Fernando!

Thank You, Riad! You have the usual, unusual puzzles - very interesting!
Good luck and new faery tasks!

?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!