The New Sudoku Players' Forum

by **jovi_al01** » Mon Jul 26, 2021 9:01 pm

Code: Select all: .-------.-------.-------. | 2 3 4 | 6 . . | . . . | | 1 . 5 | . 2 . | 6 . . | | . 7 6 | . 5 . | 4 2 . | +-------+-------+-------+ | . . . | 2 1 8 | . . . | | . . . | 5 . 7 | 3 6 . | | . . . | . 3 6 | . . 2 | +-------+-------+-------+ | . . 7 | . . . | 2 3 4 | | . 2 . | . . . | 1 . 5 | | . . . | . . . | . 7 6 | .-------.-------.-------. 2346.....1.5.2.6...76.5.42....218......5.736.....36..2..7...234.2....1.5.......76

this is a puzzle i set a while ago, and i thought some of you might appreciate it! it should crack after you find the opening.

by **eleven** » Tue Jul 27, 2021 6:26 am

Nice one, thanks.

Code: Select all: *--------------------------------------------------------------------------* | 2 3 4 | 6 79-8 19 | 5789 15 1789 | | 1 89 5 | 347 2 34 | 6 89 37 | | #89 7 6 | 389 5 139 | 4 2 1389 | |--------------------------+------------------------+----------------------| | 345679 4569 39 | 2 1 8 | 579 45 79 | | #89+4 1489 2 | 5 Aa49 7 | 3 6 189 | | 45789 14589 189 | 49 3 6 | 5789 145 2 | |--------------------------+------------------------+----------------------| | #89+6 1689 7 | 189 A689 5 | 2 3 4 | | b34689 2 389 | 34789 4679-8 349 | 1 89 5 | | b34589 c14589 1389 | 13489 A489 2 | 89 7 6 | *--------------------------------------------------------------------------*

Either r5c1=4 or r7c1=6 to avoid three 89's in c1.
4r5c1 -> 9r5c5 & 4r9c2 -> 8r9c5
6r7c1 -> 489r579c5
=> -8r18c5

Solves with w-wing.

by **marek stefanik** » Tue Jul 27, 2021 6:54 am

Trying for a one-stepper:

Code: Select all: +------------------------+------------------------+------------------------+ | 2 3 4 | 6 789 19 | 5789 15 1789 | | 1 89 5 | 347 2 34 | 6 89 37 | |a89 7 6 | 389 5 139 | 4 2 1389 | +------------------------+------------------------+------------------------+ | 345679 4569 39 | 2 1 8 | 579 45 79 | |a489 1489 2 | 5 *49 7 | 3 6 189 | | 45789 14589 189 | 49 3 6 | 5789 145 2 | +------------------------+------------------------+------------------------+ |a689 1689 7 | 189 b689 5 | 2 3 4 | |*34689 2 389 | 34789 c46789 349 | 1 89 5 | |*34589 *14589 1389 | 13489 *489 2 | 89 7 6 | +------------------------+------------------------+------------------------+

Almost empty rectangle: 4c5b7 / r9
ER – (4=689)r357c1 – 6r7c5 = (6-4)r8c5 = Loop
-89r4689c1, -6r7c2, -789r8c5, stte

by **totuan** » Tue Jul 27, 2021 6:56 am

eleven wrote:Either r5c1=4 or r7c1=6 to avoid three 89's in c1.

I was late with the same key point - my favourite strong links

Code: Select all: *-----------------------------------------------------------------------------* | 2 3 4 | 6 789 19 | 5789 15 1789 | | 1 89 5 | 347 2 34 | 6 89 37 | | 89 7 6 | 389 5 139 | 4 2 1389 | |-------------------------+-------------------------+-------------------------| | 345679 4569 39 | 2 1 8 | 579 45 79 | | 489 1489 2 | 5 49 7 | 3 6 189 | | 45789 14589 189 | 49 3 6 | 5789 145 2 | |-------------------------+-------------------------+-------------------------| | 689 1689 7 | 189 689 5 | 2 3 4 | | 34689 2 389 | 34789 46789 349 | 1 89 5 | | 34589 14589 1389 | 13489 489 2 | 89 7 6 | *-----------------------------------------------------------------------------*

Look at (4689)r357c1 => to avoid empty cell then (6)r7c1==(4)r5c1

Present as diagram: r5c5<>4, stte

Code: Select all: (4)r9c5* (8)r7c1----(6)r7c1=(4)r5c1* || || | (8)r9c5--r9c7=r8c8-r2c8=r2c2-(8)r7c2 | || | || | || ---------------------(8)r7c45 ---------(6)r7c5 || || || -----------------------------------------(9)r7c5 || | || (9)r9c5--(9=8)r9c7-r8c8=r2c8-r2c2=r3c1-r3c4=r1c5-(8)r7c5

Thanks for the puzzle.
totuan

by **shye** » Tue Jul 27, 2021 12:04 pm

happy to see you joined the forum jovi

Code: Select all: .------------------------.-------------------.-----------------. | 2 3 4 | 6 789 19 | 5789 15 1789 | | 1 *89 5 | 347 2 34 | 6 *89 37 | | 89 7 6 | 389 5 139 | 4 2 1389 | :------------------------+-------------------+-----------------: | 345679 4569 39 | 2 1 8 | 579 45 79 | | 489 1489 2 | 5 49 7 | 3 6 189 | | 45789 14589 189 | 49 3 6 | 5789 145 2 | :------------------------+-------------------+-----------------: |#689 *1689 7 | 189 689 5 | 2 3 4 | |#34689 2 *389 | 34789 46789 349 | 1 *89 5 | |#34589 #14589 #1389 | 13489 489 2 | 89 7 6 | '------------------------'-------------------'-----------------'

At least one of 8 or 9 in #ed cells to avoid bivalue oddagon in *ed cells
4r5c1=4r9c5 => -4r5c5
btte

by **jco** » Tue Jul 27, 2021 4:45 pm

After basics.

Let x and y be the correct digits at r3c1, r2c2 respectively.
Then, we must have the following configuration.

Code: Select all: .-----------------------------------------------------------. | 2 3 4 | 6 7xy 19 | 57y 15 17y | | 1 y 5 | 347 2 34 | 6 x 37 | | x 7 6 | 3y 5 139 | 4 2 13y | |---------------------+-------------------+-----------------| | 345679 4569 39 | 2 1 8 | 579 45 79 | | 4y 14x 2 | 5 49 7 | 3 6 1xy | | 457y 145x 1xy | 49 3 6 | 57y 145 2 | |---------------------+-------------------+-----------------| | 6y 16x 7 | 1xy 6xy 5 | 2 3 4 | | 346 2 3x | 347x 467x 349 | 1 y 5 | | 345y 145x 13y | 134y 4y 2 | x 7 6 | '-----------------------------------------------------------'

1. Grouped W-wing (4=y)r5c1-(y)r79c1=(y)r9c3-(y=4)r9c5 => -4 r5c5,r9c1

After simple elimination, we get the following

Code: Select all: .-----------------------------------------------------------. | 2 3 4 | 6 7xy 19 | 57y 15 17y | | 1 y 5 | 37 2 4 | 6 x 37 | | x 7 6 | 3y 5 139 | 4 2 13y | |---------------------+-------------------+-----------------| | 35679 569 39 | 2 1 8 | 579 4 79 | | 4y 14x 2 | 5 9 7 | 3 6 1xy | | 57y 15x 1xy | 4 3 6 | 57y 15 2 | |---------------------+-------------------+-----------------| | 6y 16x 7 | 1xy 6xy 5 | 2 3 4 | | 46-3 2 *3x | 7-3x 467x *39 | 1 *y 5 | | 35y 145 13y | 13y 4y 2 | x 7 6 | '-----------------------------------------------------------'

Candidates (3,9,x,y) at r8c368 form a locked set (389), so -3 r8c1, -(3x) r8c4.

After some eliminations

Code: Select all: .-----------------------------------------------------------. | 2 3 4 | 6 7x 19 | 57y 15 17y | | 1 y 5 | 3 2 4 | 6 x 7 | | x 7 6 | y 5 19 | 4 2 13 | |---------------------+-------------------+-----------------| | 35679 569 3 | 2 1 8 | 579 4 9 | | 4y 14x 2 | 5 9 7 | 3 6 1xy | | 57y 15x 1xy | 4 3 6 | 57y 15 2 | |---------------------+-------------------+-----------------| | 6y 16 7 | x 6y 5 | 2 3 4 | | 46 2 3x | 7 46 39 | 1 y 5 | | 35y 145 13y | 1 4y 2 | x 7 6 | '-----------------------------------------------------------'

HS: r1c5=7, r3c9=3, r3c6=1 (=> y=8, x=9); ste

Edit: re-posted solution with correction after step 1.

by **jovi_al01** » Tue Jul 27, 2021 6:07 pm

beautiful solves everyone

thank you for taking a look at this!

Kettle