cecbevwr wrote:Hi Suduko friends. I started the following hard (very hard?) puzzle:
*4* *5* ***
**6 **2 **9
58* 1*6 ***
*6* 82* ***
8** *** **5
*** *73 *8*
*** 7*9 *24
6** 3** 9**
*** *6* *7*
I got as far as this:
*4* 957 ***
**6 4*2 **9
58* 1*6 ***
*65 82* ***
8** 69* **5
*** 573 *8*
358 719 624
6** 348 951
*** 265 *7*
Looking at Blocks 3,6 and 9, ie columns 7,8 and 9, the following
candidates exist which I think is a "X -Wing" pattern which I don't
fully understand even after reading the explanatory notes from
www.angusj.com/sudoku/hints.php:1238 136 12368
134578 134 9
2347 34 27
1347 13479 137
12347 13469 5
124 8 126
6 2 4
9 5 1
138 7 138
I suspect candidates 1,3 and 8, which appear in each of the four
corner cells, r1c7, r1c9, r9c7 and r9c9, provide the necessary
rectangular pattern for a valid X-Wing. However, from this
point on I am stumped!! I would appreciate help in explaining
to me which candidates can be eliminated so I can proceed
further.
For what it's worth, I enjoy solving these puzzles but become
frustrated when I can't. The help I get from this forum is what
keeps me interested to learn more hints to solve these puzzles
Regards Bonsai Cec
Try this: first label columns A,B,C,D,E,F,G,H,&I and rows 1,2,3,4,5,6,7,8,&9.
The following are the steps:
I8=1
I9=3
I4=7
I3=2
I1=6
D1=9
D2=4
E3=3
E2=8
F1=7
D5=6
D6=5
D9=2
E7=1
E8=4
E5=9
A7=3
B7=5
C7=8
G7=6
H3=4
G3=7
C3=9
H6=6 (CAN ONLY BE 6)
H4=9 (CAN ONLY BE 9)
C4=5 (CAN ONLY BE 5)
G4=3 (ROW 4 CAN ONLY BE 3)
A4=4
C9=4 (BLOCK CAN ONLY BE 4)
A2=7 (COLUMN CAN ONLY BE 7)
Note 1: C1 can't be 1 since columb A1 or B2 =1 (based on A9 or B9). Since 1 is eliminated from C1, then in column C row 6 can only be 1)
Note 2: C1 can't be 2 since A6 or B6 must be 2 or 9. therefore:
C1=3 (only remaining number that can fit)
C5=7
B2=1
A1=2
B5=3
A6=9
B6=2
A9=1
B9=9
B8=7
C8=2
G2=5
H2=3
H1=8
G1=1
G9=8
H8=5
F8=8
F9=5
COMPLETE !! REGARDS DICK