The New Sudoku Players' Forum

[Mauriès Robert]

Hello, Happy New Year!
Here is my first puzzle of the year that I suggest you solve.

..........1..2.7...72..9.8...64..1..42..6..79..8..54...4.6..35...1.8..9..........

puzzle: Show

solution: Show

5-step resolution with chains of less than 10 candidates, but presenting closed sets (in bold) :
(-4r3c5)->4r3c9->4r8c6->... => -4r12c6, -4r9c5
(-2r4c8)->2r4c6->8r4c9->9r7c5->3r4c5->... => -3r4c8 => r4c8=2 + 7 placements
(-3r5c3)->5r5c3->5r4c9->8r4c6->346r2c689->4r1c3->... -3r12c3
(-7r7c9)->8r7c9->8r5c7->(5r3c7->13r35c4 & 5r5c3->3r9c3->5r9c5)->7r8c4->... => -7r7c6 => r7c6=2 et -7r8c9 => -7r9c6
(-5r5c6)->(5r3c7->8r5c7->8r7c9->7r9c9->1r3c9->3r3c4 & 5r5c3->3r9c3)->3r8c6->... 3r5 empty => r5c6=5, end

Robert

[DEFISE]

Happy new year all !

This puzzle is in W6 but here's what my program gets with whip[<=10]:

Single(s): 1r6c1, 9r1c7, 7r4c1
Box/Line: 2c7b9 => -2r7c9 -2r8c9 -2r9c8 -2r9c9
Box/Line: 9b4c2 => -9r9c2
Hidden pairs: 58b6p34 => -2r4c9 -3r4c9
whip[9]: r7n8{c1 c9}- r4c9{n8 n5}- r4n8{c9 c6}- b5n2{r4c6 r6c4}- c4n9{r6 r9}- c1n9{r9 r2}- r2n8{c1 c4}- r2n5{c4 c3}- r5n5{c3 .} => -2r7c1
Single(s): 2r7c6, 2r4c8, 2r1c9, 2r6c4, 7r6c5, 9r6c2, 9r4c5, 1r7c5, 9r9c4
whip[9]: r8n4{c9 c6}- r2n4{c6 c3}- c3n9{r2 r7}- r7n7{c3 c9}- r8n7{c9 c4}- r9c6{n7 n3}- r4c6{n3 n8}- c9n8{r4 r9}- c9n1{r9 .} => -4r3c9
Single(s): 4r3c5
whip[10]: c5n3{r9 r1}- c2n3{r1 r4}- r4c6{n3 n8}- r4c9{n8 n5}- c7n5{r5 r3}- r3c4{n5 n1}- c9n1{r3 r9}- r9n7{c9 c6}- r1c6{n7 n6}- r2c6{n6 .} => -3r9c3
whip[7]: r5n5{c7 c3}- r9c3{n5 n7}- r7c3{n7 n9}- r2n9{c3 c1}- r2n5{c1 c4}- r2n8{c4 c6}- r4n8{c6 .} => -5r4c9
STTE

[DEFISE]

I get a little better, semi-automatically: I launched the program after eliminating 2r7c1.
And finally this resolution in W9:

Single(s): 1r6c1, 9r1c7, 7r4c1
Box/Line: 2c7b9 => -2r7c9 -2r8c9 -2r9c8 -2r9c9
Box/Line: 9b4c2 => -9r9c2
Hidden pairs: 58b6p34 => -2r4c9 -3r4c9
whip[9]: r7n8{c1 c9}- r4c9{n8 n5}- r4n8{c9 c6}- b5n2{r4c6 r6c4}- c4n9{r6 r9}- c1n9{r9 r2}- r2n8{c1 c4}- r2n5{c4 c3}- r5n5{c3 .} => -2r7c1
Single(s): 2r7c6, 2r4c8, 2r1c9, 2r6c4, 7r6c5, 9r6c2, 9r4c5, 1r7c5, 9r9c4
whip[9]: r4c6{n3 n8}- b5n3{r4c6 r5c4}- r5c3{n3 n5}- c7n5{r5 r3}- r3c4{n5 n1}- c9n1{r3 r9}- c9n8{r9 r7}- c9n7{r7 r8}- r8n4{c9 .} => -3r8c6
whip[8]: r7c9{n7 n8}- c7n8{r9 r5}- r5n5{c7 c3}- r9c3{n5 n3}- r8n3{c1 c4}- r5c4{n3 n1}- r3c4{n1 n5}- c7n5{r3 .} => -7r7c3
Single(s): 9r7c3, 8r7c1, 7r7c9, 9r2c1, 8r1c2, 7r9c3
Box/Line: 6c2b7 => -6r8c1 -6r9c1
whip[4]: r4c9{n8 n5}- r5n5{c7 c3}- r2n5{c3 c4}- c4n8{r2 .} => -8r5c7
STTE

[Hajime]

Puzzle is not minimal. You can eliminate given 6 in r5c5 for the same solution. Probably a different resolution path.

Code: Select all

..........1..2.7...72..9.8...64..1..42.....79..8..54...4.6..35...1.8..9..........

[Mauriès Robert]

Hi Hajime,
Indeed the puzzle is made minimal without the 6r5c5 that we can therefore remove from the revealed candidates. Well seen, bravo !
But this does not change the difficulty level of the puzzle.
Concerning the resolution, the first 4 steps that I gave remain the same, but to continue with the same 5th step we must add this one that validates the 6L5C5:
(-6r5c3)->[ 6r5c6->1r1c6->7r1c4 & 3r5c5->5r9c5 ]->3r8c4->5r3c4->5r5c7->... => r5c3 empty => r5c5=6
Robert

[DEFISE]

For the minimal puzzle without 6r5c5 :
It is also in W6, but harder to solve in W9. I found a path with 6 whips instead of 4 :

Single(s): 1r6c1, 9r1c7, 7r4c1
Box/Line: 2c7b9 => -2r7c9 -2r8c9 -2r9c8 -2r9c9
Box/Line: 9b4c2 => -9r9c2
Hidden pairs: 58b6p34 => -2r4c9 -3r4c9 -6r5c7
Box/Line: 6r5b5 => -6r6c5
whip[9]: r7n8{c1 c9}- r4c9{n8 n5}- r4n8{c9 c6}- b5n2{r4c6 r6c4}- c4n9{r6 r9}- c1n9{r9 r2}- r2n8{c1 c4}- r2n5{c4 c3}- r5n5{c3 .} => -2r7c1
Single(s): 2r7c6, 2r4c8, 2r1c9, 2r6c4, 7r6c5, 9r6c2, 9r4c5, 1r7c5, 9r9c4
whip[9]: r8n4{c9 c6}- r2n4{c6 c3}- c3n9{r2 r7}- r7n7{c3 c9}- r8n7{c9 c4}- r9c6{n7 n3}- r4c6{n3 n8}- c9n8{r4 r9}- c9n1{r9 .} => -4r3c9
Single(s): 4r3c5
whip[7]: r5c5{n6 n3}- r4c6{n3 n8}- r5c4{n8 n1}- r5n8{c4 c7}- c7n5{r5 r3}- r3c4{n5 n3}- r2c6{n3 .} => -6r1c5
Single(s): 6r5c5
whip[9]: r4c6{n3 n8}- b5n3{r4c6 r5c4}- r5c3{n3 n5}- c7n5{r5 r3}- r3c4{n5 n1}- c9n1{r3 r9}- c9n8{r9 r7}- c9n7{r7 r8}- r8n4{c9 .} => -3r8c6
whip[8]: r7c9{n7 n8}- c7n8{r9 r5}- r5n5{c7 c3}- r9c3{n5 n3}- r8n3{c1 c4}- r5c4{n3 n1}- r3c4{n1 n5}- c7n5{r3 .} => -7r7c3
Single(s): 9r7c3, 8r7c1, 7r7c9, 9r2c1, 8r1c2, 7r9c3
Box/Line: 6c2b7 => -6r8c1 -6r9c1
whip[4]: r4c9{n8 n5}- r5n5{c7 c3}- r2n5{c3 c4}- c4n8{r2 .} => -8r5c7
STTE