The New Sudoku Players' Forum

by **RSW** » Sat Oct 31, 2020 1:28 am

A non-minimal (so-called "challenging") puzzle from the local newspaper, with 3 clues removed to make it minimal and more interesting.

Code: Select all: . . .|. . 3|2 . . . 4 1|. . .|. . . . . .|8 . .|. 7 3 -----+-----+----- . . 5|. . 7|. 9 . . 6 .|4 9 .|. . 5 9 . .|. 1 .|3 . . -----+-----+----- . . .|. . .|. . . 8 2 .|. . .|. . . . . .|5 4 .|. . 6

000003200041000000000800073005007090060490005900010300000000000820000000000540006

by **pjb** » Sat Oct 31, 2020 4:10 am

Two chains:
1) (1=8)r4c2 - (8=5)r16c2 - (5=6)r1c5 - (6=1)r19c1 => -1 r5c1, r79c2
basics (40 elims),=>

Code: Select all: 567 578 678 | 1 56 3 | 2 4 9 3 4 1 | 27 27 9 | 56 56 8 56 9 2 | 8 56 4 | 1 7 3 ------------------------+----------------------+--------------------- 24 1 5 | 36 38 7 | 68 9 24 27 6 3 | 4 9 28 | 78 1 5 9 78 478 | 26 1 5 | 3 26 47 ------------------------+----------------------+--------------------- 4567 57 4679 | 2379 2378 16 | 479 238 127 8 2 4679 | 379 37 16 | 4579 35 17 1 3 79 | 5 4 28 | 79 28 6

2) (2=6)r6c4 - (6=2)r6c8 - (2=8)r9c8 - (8=2)r9c6 => -2 r5c6, -2 r7c4; btte

Phil

by **Leren** » Sat Oct 31, 2020 7:44 pm

Two URs :

Code: Select all: *-------------------------------------------------------* |*56+7 578 678 | 1 *56 3 | 2 4 9 | | 3 4 1 | 279 27 29 | 56 56 8 | |*56+2 59 269 | 8 *56 4 | 1 7 3 | |-------------------+------------------+----------------| | 4-12 18 5 | 236 238 7 | 468 9 124 | |#127 6 3 | 4 9 28 | 78 128 5 | | 9 78 2478 | 26 1 5 | 3 268 247 | |-------------------+------------------+----------------| | 456-17 13579 4679 | 2379 2378 12689 | 4789 1238 1247 | | 8 2 4679 | 379 37 169 | 4579 135 147 | |#17 1379 79 | 5 4 1289 | 789 1238 6 | *-------------------------------------------------------*

1: UR Type 3 (56) r13c15 + r59c1 => - 12 r4c1, -17 r4c7

Code: Select all: *--------------------------------------------------* | 567 *58-7 *68-7 | 1 56 3 | 2 4 9 | | 3 4 1 | 279 27 29 | 56 56 8 | | 256 59 269 | 8 56 4 | 1 7 3 | |-----------------+-----------------+--------------| | 4 18 5 | 236 238 7 | 68 9 12 | | 12 6 3 | 4 9 28 | 7 128 5 | | 9 *78 *278 | 26 1 5 | 3 268 4 | |-----------------+-----------------+--------------| | 56 1359 469 | 2379 2378 12689 | 489 1238 127 | | 8 2 469 | 379 37 169 | 459 135 17 | | 17 1379 79 | 5 4 1289 | 89 1238 6 | *--------------------------------------------------*

2. Hidden UR (78) r16c23 => - 7 r1c23; stte

Leren

by **Cenoman** » Sun Nov 01, 2020 5:22 pm

Another solution in two steps with UR(56)r13c5:

Code: Select all: +-------------------------+------------------------+-----------------------+ | a567 578 678 | 1 56 3 | 2 4 9 | | 3 4 1 | 279 27 29 | 56 56 8 | | b256 59 c269 | 8 56 4 | 1 7 3 | +-------------------------+------------------------+-----------------------+ | 124 18 5 | 236 238 7 | 468 9 124 | | 127 6 3 | 4 9 28 | 78 128 5 | | 9 78 2478 | 26 1 5 | 3 268 247 | +-------------------------+------------------------+-----------------------+ | 14567 13579 c4679 | 2379 2378 12689 | 4789 1238 1247 | | 8 2 c4679 | 379 37 169 | 4579 135 147 | | 1-7 1379 c79 | 5 4 1289 | 789 1238 6 | +-------------------------+------------------------+-----------------------+

UR(56)r13c15 using internals
(7)r1c1 == (2)r3c1 - (2=4697)r3789c3 => -7 r9c1; 7 placements & basics

Code: Select all: +----------------------+---------------------+---------------------+ | 567 578 678 | 1 56 3 | 2 4 9 | | 3 4 1 | 27 27 9 | 56 56 8 | | 56 9 2 | 8 56 4 | 1 7 3 | +----------------------+---------------------+---------------------+ | 24 1 5 | 36 38 7 | 68 9 24 | | 27 6 3 | 4 9 28 | 78 1 5 | | 9 78 478 | 26 1 5 | 3 26 47 | +----------------------+---------------------+---------------------+ | 4567 57 4679 | 2379 2378 16 | 479 238 127 | | 8 2 4679 | 379 37 16 | 4579 35 17 | | 1 3 79 | 5 4 28 | 79 28 6 | +----------------------+---------------------+---------------------+

UR(56)r13c15 using single internal (type 1): +7r3c1; ste

N-3 Version 1