Small change from earlier, we will have instant grading after all. This means the answer for the optimizers will show red highlight, but we will adjust it in the backend later, so ignore that.

The Puzzle Booklet is now available, submissions can start 2 minutes from now.

Hello, for puzzle 2 Tourist how do we write an answer as for example SW ? Format answer says only 8 times. Should we write S instead of SW ?

Hello everybody.
One minor comment: the points awarded on some puzzles don't always match up between the puzzle booklet and the submission page.
Puzzle booklet: points awarded for puzzles 1, 3, 4, 5, 7 and 8 are respectively 4, 6, 4, 5, 12 and 7;
submission page: points awarded for puzzles 1, 3, 4, 5, 7 and 8 are respectively 5, 5, 5, 6, 11 and 11.

8 times here just means describing 8 cells, but there was an error in the backend that would show the box red if you entered more than 8 characters, I've changed that now. For SW just put SW in the string.

Thanks for letting us know. The Puzzle booklet had some late changes and the submission page points are from an earlier iteration. We will fix this soon, but Puzzle booklet has the accurate set of points. Sorry for the confusion.

Hi!
In puzzle 12, is it possible to put a zero in the outside clue? Zero means that there is no circle in that direction.

if+you+were+allowed+to+have+a+clue+pointing+at+0+circles+i+guess+it+would+be+a+1+and+not+a+0%0aAlso+interested+in+the+answer+to+that+question

There%E2%80%99s+a+tiny+mistake+in+the+booklet%2C+optimizer+12%2C+the+answer+key+for+the+example+should+begin+with+17%2E4+%2826+minus+8%2E6%29

%3E+Barbitos%0D%0AThat%27s+a+good+point%2C+I+guess+it%27s+the+same+logic+as+0%21%3D1%2E%0D%0AAnd+for+clarification+of+the+rule%2C+I+would+like+to+add+%E2%80%9Cthe+outer+clue+must+point+to+one+or+more+circles%E2%80%9D%2E

Edited by SP1 2025-04-18 10:51 PM

Hi!
Zero cannot be specified. Put only the products of the numbers in circles.

%5BQUOTE%5DL00ping007+%2D+2025%2D04%2D18++10%3A16+PM%0D%0A%0D%0AThere%E2%80%99s+a+tiny+mistake+in+the+booklet%2C+optimizer+12%2C+the+answer+key+for+the+example+should+begin+with+17%2E4+%2826+minus+8%2E6%29%5B%2FQUOTE%5D%0D%0AI%27ll+fix+it%2C+thanks%21

%5BQUOTE%5DSP1+%2D+2025%2D04%2D18++10%3A51+PM%0D%0A%0D%0A%3E+Barbitos%0D%0AThat%27s+a+good+point%2C+I+guess+it%27s+the+same+logic+as+0%21%3D1%2E%0D%0AAnd+for+clarification+of+the+rule%2C+I+would+like+to+add+%E2%80%9Cthe+outer+clue+must+point+to+one+or+more+circles%E2%80%9D%2E%5B%2FQUOTE%5D%0D%0AIf+there+is+only+one+circle+in+a+direction%2C+the+product+will+be+the+number+in+the+circle%2E%0D%0A

Technically the product of no numbers is 1, so it could be interpreted that a 1 clue in a diagonal is satisfied by having no circles in that diagonal

Can you please confirm that if a diagonal has no circles, you're not allowed to clue it?

Does this mean there are penalties for wrong submissions in puzzle 1-9, and they really count in the final result?

If there are no circles in the selected direction, then you cannot enter a number in the yellow square.

Unfortunately yes, I suppose its still better than a would-be 0 with a wrong submission.

OK, Thank you!

Names+Hitori%3a+I+think+words+like+Sarayu+and+Joeri+cannot+be+used.+It+is+confusing+that+they+are+on+the+list.

I+can%27t+fully+understand+the+rules+of+9%2E+Mosaic+with+digits%3A%0D%0A+%2D+the+%22diagonal+direction%22+pointed+by+an+arrow+is+always+a+45%C2%B0+directions%2C+regardless+of+the+cell%27s+shape%3F+Or+is+it+perpendicular+to+the+diagonal+of+the+arrow%27s+cell%3F%0D%0A+%2D+%22number+of+diagonals+parallel%22+means+%22parallel%22+or+%22of+the+same+type%22%3F+I+mean%3A+two+diagonals+%22%2F%22+in+a+1x1+cell+and+in+a+2x1+cell+should+be+considered+%22parallel%22%3F

These are the names of the participants of April Contest 2024. Everyone decides for themselves which words to use and which not to use.

%F0%9F%8C%9F

Do+overlapping+words+attract+disqualification+of+the+solution%3f

Yes.

A question for LMI:
On this discussion page I see "27 posts - Page 1 of 2". (After my post, it will probably say 28 posts.)
On page 1 I see 25 posts, all is good.
But when I click to page 2 I see nothing (no posts) at all. I have tried this in different devices and different browsers.
Is something wrong, preventing posts 26_PLUS_ from displaying?

[Edit: I now see this post at the top of page 2. Perhaps 2 posts were deleted and the website was confused. But I still count 26 posts, not 28.)

Edited by kiwijam 2025-04-26 3:01 AM

A question for Riad:

After reading Anurag's question, I think there are 2 ways to understand Name Hitori.
1) Are the words chosen by the contestant, using parentheses? 2) Or are the words chosen by wordlist only?

For example, my row is "KENDOWXYZ". This includes the letters "KEN" and "ENDO".
1) I know I am only allowed one word here. In the answer key I enter (KEN)DOWXYZ or K(ENDO)WXYZ. The other word is ignored, and I do not count it for my score.
or 2) This row breaks the rules. Even if I enter (KEN)DOWXYZ, the puzzle is invalid and I get no score.

So we all use the same rule, do you think 1) or 2) is correct?

James, example 1) using the name KEN ENDO is correct. If you specify only one word in parentheses, the answer will be accepted. It is not allowed to use parentheses like this: (K(EN)DO)WXYZ.

%D0%97%D0%B4%D1%80%D0%B0%D0%B2%D1%81%D1%82%D0%B2%D1%83%D0%B9%2C%D0%A0%D0%B8%D0%B0%D0%B4%0D%0A%D0%92%D0%BE%D0%BF%D1%80%D0%BE%D1%81+%D0%BF%D0%BE+%D0%B3%D0%BE%D0%BB%D0%BE%D0%B2%D0%BE%D0%BB%D0%BE%D0%BC%D0%BA%D0%B5+11%2E%0D%0A%D0%9E%D0%B1%D1%8F%D0%B7%D0%B0%D1%82%D0%B5%D0%BB%D1%8C%D0%BD%D0%BE+%D0%BB%D0%B8+%D0%B2+%D1%81%D0%B5%D1%82%D0%BA%D0%B5+%D0%B4%D0%BE%D0%BB%D0%B6%D0%BD%D1%8B+%D0%B2%D1%81%D0%B5+%D1%81%D0%BB%D0%BE%D0%B2%D0%B0+%D0%BF%D0%B5%D1%80%D0%B5%D1%81%D0%B5%D0%BA%D0%B0%D1%82%D1%8C%D1%81%D1%8F+%D0%BF%D0%BE+%D0%BF%D1%80%D0%B0%D0%B2%D0%B8%D0%BB%D0%B0%D0%BC+%D0%BA%D1%80%D0%BE%D1%81%D1%81%D0%B2%D0%BE%D1%80%D0%B4%D0%B0%3F%0D%0A%D0%92%D0%BE%D0%B7%D0%BC%D0%BE%D0%B6%D0%BD%D0%BE+%D0%BB%D0%B8+%D1%82%D0%B0%D0%BA%D0%BE%D0%B5+%D0%B7%D0%B0%D0%BF%D0%BE%D0%BB%D0%BD%D0%B5%D0%BD%D0%B8%D0%B5+%D1%81%D1%82%D1%80%D0%BE%D0%BA%D0%B8+%D0%B1%D0%B5%D0%B7+%D0%BF%D0%B5%D1%80%D0%B5%D1%81%D0%B5%D1%87%D0%B5%D0%BD%D0%B8%D0%B9+%28+ARTHEJOYU%29%2DART%2DHE%2DJO%2DYU+%3D+4+%D1%81%D0%BB%D0%BE%D0%B2%D0%B0+%D0%B8+%D1%80%D0%B0%D0%B7%D1%80%D0%B5%D1%88%D0%B0%D0%B5%D1%82%D1%81%D1%8F+%D0%BB%D0%B8+%D0%B2+%D1%81%D0%B5%D1%82%D0%BA%D0%B5+%D0%BE%D1%82%D1%81%D1%83%D1%82%D1%81%D1%82%D0%B2%D0%B8%D0%B5+%D1%87%D0%B5%D1%80%D0%BD%D1%8B%D1%85+%D0%BA%D0%BB%D0%B5%D1%82%D0%BE%D0%BA%3F%0D%0A%D0%94%D0%BC%D0%B8%D1%82%D1%80%D0%B8%D0%B9%2E

LOL%2c+this+is+a+debacle.++Admin%3a+please+delete+my+submission.+++I+do+not+want+to+enter+anymore.+Thank+you.+BTW%2c+the+reply+is+still+unclear+and+does+not+help.+The+last+reply+(to+me)+meant+something+diametrically+opposite.+Things+need+to+be+made+explicit+as+this+is+only+a+test+of+logic.

@anurag The example of "Name Hitori" contains the name "AOKI" without counting it among the valid words, since it overlaps "NAOKI". Nevertheless, the grid is considered to be valid. Hence, I guess that a valid grid can contain words overlapping other words, as long as they are not counted. At least, that is what I understand from the example.
Unfortunately, you're not the only one who misunderstood the first answer of Riad: this is my case too, so I understand your frustration.

%5BQUOTE%5Dkrasnosulinec1797+%2D+2025%2D04%2D26++4%3A05+PM%0D%0A%0D%0A%D0%97%D0%B4%D1%80%D0%B0%D0%B2%D1%81%D1%82%D0%B2%D1%83%D0%B9%2C%D0%A0%D0%B8%D0%B0%D0%B4%0D%0A%D0%92%D0%BE%D0%BF%D1%80%D0%BE%D1%81+%D0%BF%D0%BE+%D0%B3%D0%BE%D0%BB%D0%BE%D0%B2%D0%BE%D0%BB%D0%BE%D0%BC%D0%BA%D0%B5+11%2E%0D%0A%D0%9E%D0%B1%D1%8F%D0%B7%D0%B0%D1%82%D0%B5%D0%BB%D1%8C%D0%BD%D0%BE+%D0%BB%D0%B8+%D0%B2+%D1%81%D0%B5%D1%82%D0%BA%D0%B5+%D0%B4%D0%BE%D0%BB%D0%B6%D0%BD%D1%8B+%D0%B2%D1%81%D0%B5+%D1%81%D0%BB%D0%BE%D0%B2%D0%B0+%D0%BF%D0%B5%D1%80%D0%B5%D1%81%D0%B5%D0%BA%D0%B0%D1%82%D1%8C%D1%81%D1%8F+%D0%BF%D0%BE+%D0%BF%D1%80%D0%B0%D0%B2%D0%B8%D0%BB%D0%B0%D0%BC+%D0%BA%D1%80%D0%BE%D1%81%D1%81%D0%B2%D0%BE%D1%80%D0%B4%D0%B0%3F%0D%0A%D0%92%D0%BE%D0%B7%D0%BC%D0%BE%D0%B6%D0%BD%D0%BE+%D0%BB%D0%B8+%D1%82%D0%B0%D0%BA%D0%BE%D0%B5+%D0%B7%D0%B0%D0%BF%D0%BE%D0%BB%D0%BD%D0%B5%D0%BD%D0%B8%D0%B5+%D1%81%D1%82%D1%80%D0%BE%D0%BA%D0%B8+%D0%B1%D0%B5%D0%B7+%D0%BF%D0%B5%D1%80%D0%B5%D1%81%D0%B5%D1%87%D0%B5%D0%BD%D0%B8%D0%B9+%28+ARTHEJOYU%29%2DART%2DHE%2DJO%2DYU+%3D+4+%D1%81%D0%BB%D0%BE%D0%B2%D0%B0+%D0%B8+%D1%80%D0%B0%D0%B7%D1%80%D0%B5%D1%88%D0%B0%D0%B5%D1%82%D1%81%D1%8F+%D0%BB%D0%B8+%D0%B2+%D1%81%D0%B5%D1%82%D0%BA%D0%B5+%D0%BE%D1%82%D1%81%D1%83%D1%82%D1%81%D1%82%D0%B2%D0%B8%D0%B5+%D1%87%D0%B5%D1%80%D0%BD%D1%8B%D1%85+%D0%BA%D0%BB%D0%B5%D1%82%D0%BE%D0%BA%3F%0D%0A%D0%94%D0%BC%D0%B8%D1%82%D1%80%D0%B8%D0%B9%2E%5B%2FQUOTE%5D%0D%0A%D0%94%D0%B8%D0%BC%D0%B0%2C+%D0%B2+%D0%BC%D0%BE%D1%91%D0%BC+%D0%BF%D1%80%D0%B8%D0%BC%D0%B5%D1%80%D0%B5+XIU+%28%D1%81%D0%BC%2E+%D0%BF%D0%BE%D1%81%D0%BB%D0%B5%D0%B4%D0%BD%D0%B8%D0%B9+%D1%81%D1%82%D0%BE%D0%BB%D0%B1%D0%B5%D1%86%29+%D0%BD%D0%B5+%D0%BF%D0%B5%D1%80%D0%B5%D1%81%D0%B5%D0%BA%D0%B0%D0%B5%D1%82%D1%81%D1%8F+%D1%81+%D0%BF%D1%80%D0%BE%D1%87%D0%B8%D0%BC%D0%B8+%D0%B3%D0%BE%D1%80%D0%B8%D0%B7%D0%BE%D0%BD%D1%82%D0%B0%D0%BB%D1%8C%D0%BD%D1%8B%D0%BC%D0%B8+%D1%81%D0%BB%D0%BE%D0%B2%D0%B0%D0%BC%D0%B8%2E+%D0%9F%D1%80%D0%B0%D0%B2%D0%B8%D0%BB%D0%B0+%D0%BA%D0%BB%D0%B0%D1%81%D1%81%D0%B8%D1%87%D0%B5%D1%81%D0%BA%D0%BE%D0%B3%D0%BE+%D0%BA%D1%80%D0%BE%D1%81%D1%81%D0%B2%D0%BE%D1%80%D0%B4%D0%B0+%D0%B7%D0%B4%D0%B5%D1%81%D1%8C+%D0%BD%D0%B5+%D0%BE%D0%B1%D1%8F%D0%B7%D0%B0%D1%82%D0%B5%D0%BB%D1%8C%D0%BD%D0%BE+%D1%81%D0%BE%D0%B1%D0%BB%D1%8E%D0%B4%D0%B0%D1%82%D1%8C%2E%0D%0A%D0%92+%D1%82%D0%B2%D0%BE%D1%91%D0%BC+%D0%B7%D0%B0%D0%BF%D0%BE%D0%BB%D0%BD%D0%B5%D0%BD%D0%B8%D0%B8+%D1%81%D0%BA%D0%BE%D0%B1%D0%BA%D0%B8+%D1%81%D0%BB%D0%B5%D0%B4%D1%83%D0%B5%D1%82+%D1%80%D0%B0%D1%81%D1%81%D1%82%D0%B0%D0%B2%D0%B8%D1%82%D1%8C+%D0%B8%D0%BD%D0%B0%D1%87%D0%B5%3A+%28ART%29%28HE%29%28JO%29%28YU%29%2E++%D0%92+%D1%82%D0%B0%D0%BA%D0%BE%D0%BC+%D0%B2%D0%B8%D0%B4%D0%B5+%D1%81%D1%82%D1%80%D0%BE%D0%BA%D0%B0+%D0%BF%D1%80%D0%B8%D0%B5%D0%BC%D0%BB%D0%B5%D0%BC%D0%B0%2E%0D%0A%D0%A7%D1%91%D1%80%D0%BD%D1%8B%D1%85+%D0%BA%D0%BB%D0%B5%D1%82%D0%BE%D0%BA+%D0%B1%D1%8B%D1%82%D1%8C+%D0%BD%D0%B5+%D0%B4%D0%BE%D0%BB%D0%B6%D0%BD%D0%BE%2C+%D0%B2%D0%B5%D0%B4%D1%8C+%D0%BF%D0%BE+%D1%83%D1%81%D0%BB%D0%BE%D0%B2%D0%B8%D1%8E+%22%D0%BD%D0%B5%D0%B8%D1%81%D0%BF%D0%BE%D0%BB%D1%8C%D0%B7%D0%BE%D0%B2%D0%B0%D0%BD%D0%BD%D1%8B%D0%B5+%D0%BA%D0%BB%D0%B5%D1%82%D0%BA%D0%B8+%D0%BD%D0%B0%D0%B4%D0%BE+%D0%B7%D0%B0%D0%BF%D0%BE%D0%BB%D0%BD%D0%B8%D1%82%D1%8C+%D0%BB%D1%8E%D0%B1%D1%8B%D0%BC%D0%B8+%D0%B0%D0%BD%D0%B3%D0%BB%D0%B8%D0%B9%D1%81%D0%BA%D0%B8%D0%BC%D0%B8+%D0%B1%D1%83%D0%BA%D0%B2%D0%B0%D0%BC%D0%B8%22%2E

Paul, thanks for your detailed answer to Anurag. The example is eloquent.

%D0%9F%D1%80%D0%BE%D1%88%D1%83+%D0%B0%D0%B4%D0%BC%D0%B8%D0%BD%D0%B8%D1%81%D1%82%D1%80%D0%B0%D1%82%D0%BE%D1%80%D0%B0+%D0%9E%D0%A2%D0%9C%D0%95%D0%9D%D0%98%D0%A2%D0%AC+%D0%BC%D0%BE%D1%8E+%D0%B7%D0%B0%D1%8F%D0%B2%D0%BA%D1%83%2E

Simple explanation here I think, unless I misunderstood the question. Two posts were pending approval as they were first time posts from people, and some of us were away for the weekend and slow to approve it.

Preliminary+results+have+been+published%2E+%0D%0AI+ask+Christian+to+check+his+Hitori%2E+%0D%0ANikola+and+Du%D1%81%2C+please+check+your+answers+to+puzzle+12%2E+The+lines+should+not+overlap%2E+

Oh+wow%2C+thank+you+for+a+great+contest+Riad%21+The+puzzles+were+hard%2C+but+they+are+always+hard%2E+And+thank+you+to+all+the+contestants+with+short+names%2E+%F0%9F%98%8E%0D%0AI+don%27t+think+anybody+has+got+100+points+before%2E+If+it+is+useful+for+others%2C+I+will+share+some+thoughts+on+how+I+approached+them%2E%0D%0A%0D%0AOpti%2DSumdoku%3A+%0D%0AThe+first+step+was+to+find+a+grid+with+a+high+Samedoku+score%2E+I+looked+at+patterns+for+each+digit+separately%2E+It+is+not+possible+to+place+a+digit+in+9+cells+so+that+it+counts+18+times+to+the+sum+%28when+every+digit+can+see+another+digit+in+both+diagonal+directions%29%2E+The+best+possible+is+16+times+%28see+the+9s+in+my+solution%29%2E+But+not+all+digits+can+be+16+%2D+the+best+grid+overall+has+%7B16%2C+15%2C+15%2C+14%2C+14%2C+14%2C+14%2C+14%2C+14%7D+for+the+Samedoku%2E+I+think+Carlos+has+the+same+grid+as+me%2E%0D%0AThe+second+step+is+to+take+away+as+many+digits+as+possible%2E+Check+for+uniqueness%2C+try+another+digit%2E+Eventually+you+will+get+down+to+%7E22+clues%2E%0D%0AThe+last+step+is+to+choose+which+digit+goes+in+each+part+of+the+grid+pattern%2E+Calculate+16%2F15%2F14+minus+the+number+of+hints+remaining+%28e%2Eg%2E+9+gets+the+best+place+%3D+16%2D1%2C+8+gets+the+14%2D0%2C+7+gets+15%2D2%29%2E+%0D%0APlease+don%27t+try+to+solve+my+classic+sudoku%21+It+is+unique%2C+but+it+needs+a+lot+of+Xwings%2C+Ywings%2C+chains%2E%2E%2E+%F0%9F%98%AD%0D%0A%0D%0AName+Hitori%3A%0D%0AI+decided+to+use+all+the+2%2Dletter+and+3+words%2C+and+many+4s%2C+and+I+ignored+all+5%5FPLUS%5F+words%2E%0D%0AIt+is+easy+to+have+too+many+blacks%2C+or+not+enough+blacks%2C+so+I+started+by+trying+to+intersect+many+4%2Dwords+together%2E%0D%0AI+found+a+4x4+with+6+4%2Dwords+inside%2C+I+put+that+in+the+bottom%2Dleft+corner%2E+I+found+another+4x4+with+6+words+inside%2E+When+I+put+that+in+the+bottom%2Dright%2C+the+common+letters+%28e%2Eg%2E+ADEM%2DENDO%29+helped+fill+90%25+of+those+cells+with+black+or+white%2E+I+filled+the+top%2Dright+with+4%2Dwords+too%2C+sometimes+choosing+letters+for+Hitori%2C+sometimes+choosing+for+intersection%2E+At+the+end+I+put+the+final+2%2D+and+3%2Dwords+in+the+gaps%2E+I+had+two+empty+cells%2E+One+I+used+to+finish+the+Hitori%2C+and+one+was+a+bonus+point%2E%0D%0A%0D%0AThreads+With+Knots%3A%0D%0AI+wanted+to+start+with+long+diagonal+lines+for+the+1st%2C+3rd%2C+5th%2C+7th+sections+to+get+a+high+length%2E+I+put+small+numbers+near+the+corners%2E+The+8%2C5%2C3%2C7+clues+define+knots+1+to+7%2E+The+2+clue+is+not+needed%2C+but+it+did+give+lots+of+empty+squares+on+the+long+diagonal%2E+%0D%0AThen+I+switched+to+finding+a+unique+solution+with+small+clues%2E+Thread+length+was+less+important+now%2E+Putting+clues+on+the+same+parity%2Fcolour+diagonals+helped+too%2E+I+found+two+medium+numbers+%289%2C+13%29+to+finish%2E%0D%0ASP1+and+EKBM+both+had+much+better+clues+than+me%2C+but+my+long+thread+was+important%2E+It+is+possible+to+have+length+%3E+100%2C+but+then+you+need+too+many+big+clues+to+make+it+unique%2E

Riad, thanks for organizing a great contest!
And congratulations to kiwijam for a perfect win!!!
Thanks also to the LMI team for running the event.
I had not participated in this contest for a few years, but I really enjoyed it.

I especially like prob. 7 and 12.
I didn't have time to fix my solution for 12 because it was the last day of the contest when I realized that the length of lines was important.I regret that.
Anyway, I think prob.12 is a really good optimization setup!

I like optimization puzzles very much, and I am very happy to see the April Contest where I can enjoy them.
I'm planning to hold an optimization contest at a local site in Japan.
I hope that the fun of optimization will spread more and more.

Edited by SP1 2025-04-29 10:13 PM

Thanks a lot to everyone!
Congratulations to James, Takuma and Paul!
Success in optimization problems in 2025 earned more points than ever. James had a very impressive victory. Only two participants managed to score points in all optimizations. Takuma, great result! Interestingly written in the two posts above. I wish Takuma success in organizing the optimization contest in Japan.
There were questions like: Why ban word overlapping in Hitori? I think through the answer format so that it is convenient for the organizers. A lot of parentheses can prevent Deb from forming grids with solutions. For clarity, it is better to place the parentheses sequentially. Thanks to the LMI team, Deb and Prasanna, and a special thanks to Kota for the long-term support!

Thanks Riad and well done James! Are there solutions available to the puzzles? I had a tough time with some of them and was hoping to work through them with the solutions.