Calendar Puzzle "Rhombus" | Hacker News Reader

Calendar Puzzle "Rhombus"

praxispuzzles.com

59 pointsxyzzy_plugh24 comments

I have the "A Puzzle A Day" https://www.dragonfjord.com/product/a-puzzle-a-day/ since a few years and I have thoroughly enjoyed it.

All dates are possible and most (all?) have multiple solutions.

Was just about to link to this one!

Creator here. That puzzle started my search into this type of puzzle. But in the end my puzzle is harder, because it also contains the day of the week and has the most "irregular" puzzle pieces possible.

Nice, but it's only available in English sadly, there's a link that says "see kalenderpuzzel "Ruit" for the Dutch version" (I'd prefer French but Dutch would do as well) but that page says "De maanden en dagen van de week zijn in het Engels".

The "square" one is in Dutch but sold out and the Rotterdam one in English only.

But I like that idea, apparently it's not the first puzzle of this kind but I didn't know about them.

Creator here. If there is enough demand I can make a French version. Ordering a new batch of lasercut wood cost me $20, so I have a minimum batch size of 20.

Have they made it so impossible dates are impossible, I wonder?

Doesn't seem like it. Using the interactive board on the website I was able to produce a solution that only revealed numbers.

Creator here. No, you can arrange the puzzle pieces to make dates that don't exist, like Monday February 31. Actually there may be "impossible" dates, because I didn't check for them, but I guess all combinations of days of the week, day of the month and month are possible. And also many non-dates, like 1, 2, 3. But good point: alle possible dates have at least 1 solution. Disclaimer: I sell these puzzles for a little more than the raw material.

Looks like a really nice puzzle. Congrats.

Great puzzle. Do you ship internationally?

not OP but yes

So nice! Do you create them entirely algorithmically, or do you use the solver just to verify that every date is possible?

I wrote 2 solvers in Python. One that loops through all possible dates and searches for a solution. And one that loops through all solutions and checks if they form a date or not. And luckily both gave the same answers.

How did you select the piece shapes to ensure there was always a solution?

Actually I tried a lot of different combinations of piece shapes to find the "hardest" set of pieces that can still solve all possible dates. "Hard" is subjective, but I mean pieces with multiple protrusions.

Seems pretty hard! Even the easy example.

Creator here. I sometimes advise people not to focus on today's date, but a date in the following week. Then you have more time to find a solution!

That's really creative. Did the creator come up with the design himself?

Creator here. Yes I did. Used some existing puzzles as inspiration. See https://praxispuzzles.com/calendar_puzzle_square

Those particular rhombuses are typically known as "squares"

I thought the same thing, but it seems that certain dates would make it so there is one square ("rhombus") and one (non-square) rectangle (e.g. Feb 15).

So rather than 3 rhombuses – or 3 squares – perhaps it's 3 squares of 1 square and 1 rectangle. (Perhaps the positions of the puzzle pieces make it such that it truly is 3 squares)!

Announcing new Diamond Shreddies!

https://www.youtube.com/watch?v=bccNH82DIo0

https://www.youtube.com/watch?v=hF_2yHXD_CU

(and...neat puzzle...nice job, creator!)

Creator here. I know, I know, the "rhombuses" are just rotated "squares", but I already had a calendar puzzle "Square", so that's why.

Ooh, nice white elephant gift idea for work. I never know what to give.

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