Blocku (part II)

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Blocku (part II)

Blocku is a logic-based number-placement puzzle. It is distinct from but shares some properties and rules with Str8ts.
Rules:
•Each row and column are divided into two compartments by a black cell
•Each compartment, vertically or horizontally, must contain a straight – a set of consecutive numbers, but in any order. For example: 7, 6, 4, 5 is valid, but 1, 3, 8, 7 is not.
•Black cells don’t have numbers
•For a 10 by 10 Puzzle:
•Every row must include numbers from 1 to 9
•Every column must include numbers from 1 to 9

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Posts: 79
Joined: 31 July 2019

Re: Blocku (part II)

Solved the second example by hand. IMHO it was much the same standard as the first one, solvable using only basics. Perhaps some of the the HI/LO decisions at the start required a bit more care.

Leren
Leren

Posts: 4202
Joined: 03 June 2012

Re: Blocku (part II)

Leren wrote:Solved the second example by hand. IMHO it was much the same standard as the first one, solvable using only basics. Perhaps some of the the HI/LO decisions at the start required a bit more care.

Leren

Hi Leren,

I appreciate your constructive comments, the puzzles are generated by a program that I've written, the computer calculates the difficulty of the puzzles based on how many times the computer has to take a guess, the difficulty of the first one was 1, and the second one was 9, If I'm not mistaken I have more difficult ones which I'll post soon. note that the computer program is not as smart as humans, so it takes more guesses than needed.

Thanks again,

-Kousha

Posts: 79
Joined: 31 July 2019

Re: Blocku (part II)

Perhaps I can explain why this puzzle started so easily for me. It's due to my Str8ts background, where Compartment Interactions in the same row or column and the resulting HI/LO decisions are Bread and Butter moves.

The clue 8 in r1c9 was a dead giveaway. Given a 7/2 compartment split in Row 1 => r1c10 can then only be 8 and r2c10 must also then be 8. Next in Column 10 the lower compartment must be in the range 1-7, and given the 8/1 compartment split in Row 7, r7c10 can only be 1 or 9, and since it can't be 9 it must be 1. Next, in Column 3 the upper compartment can only be 1-3 or 7-9, but the range of the first compartment in Row 1 is 1-7 so r3c123 must be 123. In Column 5 given a 7/2 compartment split and 8 in the upper compartment, it's range can only be 3-9 and r89c5 must therefore be 12. Then given the 7/2 compartment split in Row 10 the larger compartment range must be 1-7 and r10c12 must be 98 and since there is a clue 8 in r7c1, r10c1 = 9 and r10c2 = 8. In Row 4 the 8/1 compartment split => r4c1 = 19, but r10c1 = 9 so r4c1 = 1. In Row 6 the LH compartment can only be 123 or 789, but since the upper compartment in Column 2 is already 123, it can only be 789, and given the values in r7c1 and r10c12 => r6c1 = 7, r6c2 = 9 and r6c3 = 8.

So you can see that I've been able to solve 9 cells at the start without even writing down any candidates. Now what I said above might sound quite complicated, but when you've done it many times you can do it almost without thinking.

In your solver, you can deal with these compartment split/clue arrangements on a case by case basis, to simulate what an experienced human solver would do, and reduce your need for guessing.

Leren
Leren

Posts: 4202
Joined: 03 June 2012

Re: Blocku (part II)

To summarise what I was trying to say in my previous post I'll make up a table of the basic compartment interactions and HI/LO ranges for a 9 x 9 Blocku.

Code: Select all
`Compartment Size Split     LO/HI Ranges    HI/LO Ranges                9 / 0      1-9 / -         1-9 / -                8 / 1      1-8 / 9         2-9 / 1                7  /2      1-7 / 8-9       3-9 / 1-2                6 / 3      1-6 / 7-9       4-9 / 1-3                5 / 4      1-5 / 6-9       5-9 / 1-4`

Not much to it really. Leren
Last edited by Leren on Sun Aug 11, 2019 8:50 am, edited 4 times in total.
Leren

Posts: 4202
Joined: 03 June 2012

Re: Blocku (part II)

in a 10x10: 1 and 9 can't be on the same side of a black cell. Because you have 1 black cell in a row or column, you will then eliminate so many possibilities when you solve just 1 cell. a solved cell will have obvious options that can/can't be with it on that side of the black cell. This is how restrictive the rules are!

tarek

tarek

Posts: 3752
Joined: 05 January 2006

Re: Blocku (part II)

Hi Tarek, don't quite follow you. In the first 10 x 10 puzzle there were two rows and two columns with 9 cell compartments.

However, I get your point that it's certainly a fairly simple variant, I suspect that the target audience would be those who like a few minutes relaxing diversion.

Leren
Leren

Posts: 4202
Joined: 03 June 2012

Re: Blocku (part II)

Leren wrote:Hi Tarek, don't quite follow you. In the first 10 x 10 puzzle there were two rows and two columns with 9 cell compartments
Thanks,

I should have said when there are compartments on either side of the black cell

tarek

tarek

Posts: 3752
Joined: 05 January 2006

Re: Blocku (part II)

Leren wrote:Perhaps I can explain why this puzzle started so easily for me. It's due to my Str8ts background. ... So you can see that I've been able to solve 9 cells at the start without even writing down any candidates. Now what I said above might sound quite complicated, but when you've done it many times you can do it almost without thinking.

It doesn't require much thinking even if you've never done it before. A constraint is a constraint. That's why a strong sudoku background works well for almost any constraint puzzle. I got 16 solved cells before entering pencil marks, and this was practically my second puzzle of this constraint type. In fact, the start seemed easier than the first one which only gave me eight solved cells before pm (but I think I missed some easy ones). With pencil marks they were both easy. I was hoping some non-basics would have been needed for the second one when it was advertised as more challenging.

SpAce

Posts: 2672
Joined: 22 May 2017

Re: Blocku (part II)

Hi guys,

I do appreciate you comments, they are really helpful, I'll post more challenging ones soon, you asked for It

Posts: 79
Joined: 31 July 2019

Re: Blocku (part II)

Just posted a more challenging one here: http://forum.enjoysudoku.com/blocku-part-iii-t36337.html

Hope you enjoy it