panista - 2020-04-11 5:28 PM

Puzzle 10: I have a question about the sentence "The white cells must form streets. The white area of the streets cannot contain fragments of 2x2 cells."
Is this the rule of a Town puzzle or the restriction on answers (in this case, a Town puzzle is the same as a so-called Clouds puzzle)?
For example, the mini-example without "2" is valid or invalid?

Mihalich - 2020-04-10 11:36 PM

Puzzle 7.
For numbers with cells, the use of rules a) OR b) is true. If there is a cell where the rules are applied a) AND b) is this true or is it wrong?

pranavmanu - 2020-04-11 12:21 PM

In the town puzzle mini example, going by the definition of a street being a stretch of white cells of length 2 and width 1, I can make out 6 streets in the solution for it. But the answer key gives it as 4, so have i understood it wrong?Or is there a mistake in the example's key?

anurag - 2020-04-11 2:30 PM

Someone kindly rephrase that answer, as I cannot understand any of it. I have already submitted a solution and I am pretty sure I understand what is expected. But, this new piece of information makes me believe that I may still be missing something though it is very unlikely. Organizers, either confirm that my solution follows the rules, or please confirm what is mentioned in that last reply by the author.
A slightly larger example grid might clear any doubts ( "You use this condition as given in advance" - he meant 'used' OR 'need to use'). The language seems to be the source of all confusion here. Reviewers have to step up their efforts.

Puzlifouk - 2020-04-11 5:03 PM

Hello everyone, Hello Riad,
I am extremely happy to face this contest again, which is for me the best event of the year!
And yet, because of the confinement, I forgot that it was the period and I missed the start. Why didn't you remind us earlier in a post that the start was coming? I'm really disappointed for that ...
Take care of you all.

SP1 - 2020-04-11 5:12 PM

Puzzle 10:
I think the definition of "streets" is ambiguous.
To clarify the definition, I consider a following 7x7 example:
~~~~##~
~##~##~
~##~##~
~~~~~~~
###~##~
###~##~
###~~~~

~ means white cell and # means dark cell.
I guess there are 6 streets in this grid.
detail:
R1C1 -> R1C4
R4C1 -> R4C7
R7C4 -> R7C7
R1C1 -> R4C1
R1C4 -> R7C4
R1C7 -> R7C7

Is this interpretation correct?

panista - 2020-04-11 5:28 PM

Puzzle 10: I have a question about the sentence "The white cells must form streets. The white area of the streets cannot contain fragments of 2x2 cells."
Is this the rule of a Town puzzle or the restriction on answers (in this case, a Town puzzle is the same as a so-called Clouds puzzle)?
For example, the mini-example without "2" is valid or invalid?

Riad Khanmagomedov - 2020-04-11 5:55 PM

Take a look at an example of the Town puzzle. Let's delete the given digit 2. Stefano assumed that the solution would be with a dark square. But the verifier (Deb or I) can declare the middle of the example white. The digit 2 is necessary for the uniqueness of the solution.

Riad Khanmagomedov - 2020-04-11 6:05 PM


Without the digit 2, the example does not have a unique solution.

SP1 - 2020-04-11 9:08 PM




Oh... I maybe misunderstand the rules of "Town puzzle"...
My former interpretation is as follows:


Make a Town puzzle with a unique solution in the 12x10 grid.
"Town puzzle" rules:
Place some dark rectangles, that are at least two cells wide and two cells high.
They can not touch each other, not even diagonally.
The numbers outside the grid show the number of dark cells in the corresponding row or column.
The white cells must form streets - the any stretches with a width of one cell and length at least 2.
The white area cannot contain fragments of 2x2 cells.
(<- the rules of "Clouds" + street rule)
Conditions for optimization:
Maximize N, the number of streets.
If two solutions have the same N, then the solution with the smaller sum of the given numbers is considered better.


However I read this reply and guess that the following interpretation is true:


Make a Town puzzle with a unique solution in the 12x10 grid.
"Town puzzle" rules
Place some dark rectangles, that are at least two cells wide and two cells high.
They can not touch each other, not even diagonally.
The numbers outside the grid show the number of dark cells in the corresponding row or column.
(<- exactly "Clouds" rules)
Restriction on the answer grid: (= NOT "Town puzzle" RULE!!! ONLY FOR OPTIMIZATION!!!)
The white cells must form streets - the any stretches with a width of one cell and length at least 2.
The white area cannot contain fragments of 2x2 cells.
Conditions of the optimization:
Maximize N, the number of streets.
If two solutions have the same N, then the solution with the smaller sum of the given numbers is considered better.


Which interpretation is correct? Or still misunderstanding? Please clarify!

Riad Khanmagomedov - 2020-04-11 10:11 PM


I now understand where the questions came from. In the September Contest 2010, I published the Town puzzle. When solving this puzzle, we used the condition that the white area does not have 2x2 fragments. I repeated the name of the puzzle in 2020, but without looking back at the previous work. This point probably confused the solvers. In this April Contest, I suggest using the second option that you have described.