Solution to Tarek's Fluid Drive #8 (SE 10.5)

Advanced methods and approaches for solving Sudoku puzzles

Solution to Tarek's Fluid Drive #8 (SE 10.5)

Postby gurth » Mon Nov 13, 2006 9:18 am

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Solution to Tarek's Fluid Drive #8
Code: Select all
 *-----------*
 |9..|..1|8..|
 |.6.|.3.|...|
 |..2|5..|..7|
 |---+---+---|
 |..9|...|..6|
 |.5.|...|.2.|
 |4..|...|3..|
 |---+---+---|
 |3..|..8|1..|
 |...|.4.|.8.|
 |..7|9..|..5|   SE=10.5, gsfr=99789, Suexr=930
 *-----------*

NOTE: "..." denotes steps using Simple Sudoku program.
Sub-nets are enclosed thus: (?xay...??) and sub-sub-nets thus: ((?xay...??)).

SOLUTION:

(1) -3e5(MC)

(2) ?5g3..., -3d4(Swordfish 3aeh349)... (?3a9..., -8e5(MC)... ((?1b3...??))-1b3, 8b3...??) -3a9...?? -5g3, 5g5.

(3) ?5b3..., -7e4(colours)... (?3d6...??)-3d6... (?3a9...??)-3a9..., -6h3(MC)... (?3a2...??)-3a2..., -7e5(colours)..., -7d6(X-Wing 7be16)...?? -5b3.

(4) ?5b8..., -7e4(colours)..., -8f6(MC)... (?3d6..., -4b7(MC)... ((?6g3...??))-6g3, 4g3...??) -3d6..., -8b1e15f2(Swordfish 8cdk125), (?3a9..., -2d25k257(X-Wing 2dk16), -4b7(MC), ((?1c1...??))-1c1, 8c1...??) -3a9... (?1c1..., -7e5(MC)... ((?8f3...??))-8f3, 1f3...??) -1c1, 8c1...?? -5b8.

(5) ?5f8..., -8b1e15f25(Swordfish 8cdk125), (?3a2..., -7e4(colours), -1f5(MC), -6e4(MC), -7e5(MC), -9c7(XY-Wing 179bd8e7)...??) -3a2... (?3a9...??)-3a9... (?1c1...??)-1c1, 8c1...?? -5f8, 5f6.

(6) ?5b7..., -2d4(MC), -8f5(MC)... (?3a8..., -8b1e15f2(Swordfish 8cdk125), -6h3(MC)...??) -3a8, (?3c8..., -1e15f25h2(Swordfish 1cdk125), -8e15f2(Swordfish 8cdk125)...??) -3c8...?? -5b7...

(7) ?3d6...?? -3d6...

(8) ?3a9...?? -3a9..., -4g9(MC).

(9) ?8c1...?? -8c1, 1c1.

(10) ?9c5...?? -9c5...

(11) ?1f3...?? -1f3...

(12) ?2f2...?? -2f2...End.

Tarek, a very fine and tough puzzle, it need stand back for no other in my opinion. My solution is longer than usual, with 3 sub-sub-nets.

My strategy here was what is becoming standard for me: attack the weak candidates ( those with sparse distribution, as opposed to compact distribution) in tandem (here the 5s first, with subnets on the 3s). Then, whenever no candidates appear attractive, attack the bivalue cells. (By this time, there will BE more of those.)
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Postby ravel » Mon Nov 13, 2006 2:00 pm

To compare:
This is my program's solution (no subnets, coloring, xy-wing, swordfish):
r6c5<>1, r4c5<>5, r5c5<>8, r6c5<>8, r8c1<>1, r5c6<>3, r4c1<>1, r2c1<>1, r2c3<>1, r9c6<>6, r2c1<>8, r2c3<>5, r3c2<>1, r7c8<>4, r8c9<>9, r4c6<>3, r7c3<>5, r8c3<>1, r7c3<>6, r7c2<>9, r4c8<>1, r1c2<>3
ravel
 
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Postby tarek » Tue Nov 14, 2006 12:57 am

Thanx gurth & ravel for your efforts & kind comments.......... This puzle as far as I know is the hardest which Explainer can tackle........ ...

I have no Jade to present though:(

tarek
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