The New Sudoku Players' Forum

[ab]

The idea of this thread is to post puzzles that can be solved with singles, but require many steps. Puzzles must have some symmetry. Locked candidates are not allowed, just hidden and naked singles.

Vidarino summed up how to count the number of steps quite well:
1. locate singles (naked or hidden) - but don't place any numbers
2. place all located singles in one sweep
3. rinse and repeat until solved

I'll take a leaf out of Tarek's book and post the puzzles here along with number of steps required. Let's say a puzzle needs at least 20 steps to qualify.

Code: Select all


puzzle #1 (Ruud) 26 steps
 3 . 5 | . . . | 6 . .
 . 6 . | . . . | . . 2
 . . . | . 9 . | 1 7 .
 ------+-------+------
 . . 4 | 3 . . | . . .
 8 . . | . 2 . | . . 5
 . . . | . . 9 | 3 . .
 ------+-------+------
 . 5 6 | . 1 . | . . .
 9 . . | . . . | . 4 .
 . . 3 | . . . | 9 . 8

puzzle #2 (vidarino) 22 steps
 . . 1 | 9 . 7 | 5 . 3
 . 9 . | 3 . . | . . .
 . . . | . . . | 2 7 .
 ------+-------+------
 . . 6 | 7 . . | 1 4 .
 . . . | . 6 . | . . .
 . 1 9 | . . 5 | 7 . .
 ------+-------+------
 . 8 3 | . . . | . . .
 . . . | . . 3 | . 8 .
 4 . 5 | 8 . 2 | 3 . .


puzzle #3 (vidarino) 26 steps
 . . 4 | . . 3 | . . 1
 7 . . | 6 . . | . . .
 . . 2 | 8 . . | . . .
 ------+-------+------
 3 . . | . 4 . | 8 5 .
 . 7 . | . . . | . 9 .
 . 2 8 | . 5 . | . . 3
 ------+-------+------
 . . . | . . 2 | 9 . .
 . . . | . . 6 | . . 7
 1 . . | 5 . . | 3 . .


puzzle #4 (Ruud) 25 steps
 8 . . | . 7 2 | . 3 6
 5 . . | 3 . . | . . .
 . . . | . . 8 | . 9 .
 ------+-------+------
 . . 1 | . . . | . . .
 4 . . | 6 . 5 | . . 8
 . . . | . . . | 3 . .
 ------+-------+------
 . 2 . | 8 . . | . . .
 . . . | . . 4 | . . 1
 6 1 . | 2 9 . | . . 4

puzzle #5 (gsf) 20 steps
 . . . | . . . | . . .
 . 5 6 | 1 . 9 | 2 7 .
 7 . 9 | . . . | 1 . 4
 ------+-------+------
 . 3 . | 6 . 8 | . 1 .
 . . . | . . . | . . .
 . 6 . | 9 . 4 | . 2 .
 ------+-------+------
 2 . 8 | . . . | 7 . 1
 . 9 5 | 2 . 1 | 4 6 .
 . . . | . . . | . . .

puzzle #6 (vidarino) 27 steps
 2 . . | 9 8 . | . . .
 . 7 6 | . . . | . . .
 . . . | . . . | 4 2 .
 ------+-------+------
 3 . 8 | . 4 . | . 1 .
 . . 4 | . 9 . | 3 . .
 . 6 . | . 2 . | 9 . 4
 ------+-------+------
 . 3 5 | . . . | . . .
 . . . | . . . | 8 4 .
 . . . | . 6 7 | . . 3

puzzle #7 (gsf) 20 steps
 . . . | . 5 . | . . 9
 4 5 6 | 1 . . | . . .
 . . . | 6 . . | . 1 .
 ------+-------+------
 . . . | . . 5 | . 7 4
 3 . . | . . . | . . 2
 8 1 . | 9 . . | . . .
 ------+-------+------
 . 7 . | . . 3 | . . .
 . . . | . . 8 | 5 6 1
 5 . . | . 4 . | . . .

puzzle #8 (vidarino) 25 steps
 . . . | . . . | 9 . .
 . . . | 5 . 8 | . . 4
 . 3 . | . 7 . | 1 . .
 ------+-------+------
 . . . | . . 2 | 7 . 6
 . 1 . | 4 . 3 | . 9 .
 2 . 8 | 1 . . | . . .
 ------+-------+------
 . . 9 | . 8 . | . 4 .
 8 . . | 2 . 6 | . . .
 . . 2 | . . . | . . .


puzzle #9(vidarino) 21 steps
 . 8 4 | . . . | . . .
 . 9 . | . . . | . . .
 . . . | . . 6 | 1 . 4
 ------+-------+------
 5 . 7 | 6 . . | . . .
 4 . . | . . . | . . 5
 . . . | . . 3 | 6 . 9
 ------+-------+------
 2 . 6 | 1 . . | . . .
 . . . | . . . | . 5 .
 . . . | . . . | 3 8 .

puzzle #10 (vidarino) 23 steps
 . . . | . . . | 5 . 4
 . . . | . 2 . | . 1 .
 2 9 . | 5 . . | . . 3
 ------+-------+------
 . 4 . | . 3 . | 6 . .
 6 . . | 4 8 1 | . . 5
 . . 8 | . 5 . | . 4 .
 ------+-------+------
 8 . . | . . 3 | . 9 6
 . 3 . | . 7 . | . . .
 1 . 6 | . . . | . . .
 

puzzle #11 (ruud) 25 steps
 . . . | . . 2 | 4 . .
 . . 2 | . 4 . | . 8 5
 . 6 . | . . 3 | 7 . .
 ------+-------+------
 9 . . | . 7 . | . 5 .
 . . . | . . . | . . .
 . 7 . | . 5 . | . . 4
 ------+-------+------
 . . 3 | 6 . . | . 7 .
 5 4 . | . 3 . | 1 . .
 . . 8 | 1 . . | . . .

puzzle #12 (vidarino) 21 steps
 . 1 . | . . . | 7 . .
 . . 3 | . . 1 | . . .
 . . 9 | . 3 . | . 1 6
 ------+-------+------
 . . . | . 2 . | 9 4 .
 5 . . | 1 . 9 | . . 8
 . 6 2 | . 5 . | . . .
 ------+-------+------
 7 4 . | . 6 . | 3 . .
 . . . | 2 . . | 4 . .
 . . 5 | . . . | . 6 .

puzzle #13 (JPF) 23 steps
 . . 6 | . 8 . | . . 4
 . 7 . | . . . | . 9 .
 . 3 . | 9 . 1 | . . .
 ------+-------+------
 2 5 . | . . . | . . .
 . . 4 | 3 . 7 | 1 . .
 . . . | . . . | . 2 9
 ------+-------+------
 . . . | 8 . 9 | . 1 .
 . 4 . | . . . | . 8 .
 7 . . | . 3 . | 2 . .

puzzle #14 (Ocean) 23 steps
 . . . | . 7 . | . . .
 . . 5 | . . . | 9 . .
 . 3 . | 5 . 4 | . 2 .
 ------+-------+------
 . . 3 | . 4 . | 1 . .
 4 . . | 3 . 1 | . . 9
 . . 1 | . 5 . | 8 . .
 ------+-------+------
 . 8 . | 7 . 2 | . 5 .
 . . 9 | . . . | 6 . .
 . . . | . 1 . | . . .

 puzzle #15 (Ocean) 23 steps
 1 . 3 | . . . | . 9 .
 8 . . | . . . | 5 3 4
 6 . . | . . . | . 8 .
 ------+-------+------
 . . . | . 1 4 | . . .
 . . . | 7 5 9 | . . .
 . . . | 6 3 . | . . .
 ------+-------+------
 . 1 . | . . . | . . 6
 3 5 6 | . . . | . . 8
 . 8 . | . . . | 2 . 7


puzzle #16 (ab) 20 steps
 . . . | . 6 . | . . .
 . . . | 3 . 8 | . . .
 . . 1 | 5 . 9 | 7 . .
 ------+-------+------
 . 6 5 | . . . | 1 4 .
 9 . . | . . . | . . 2
 . 7 2 | . . . | 3 6 .
 ------+-------+------
 . . 4 | 7 . 5 | 9 . .
 . . . | 8 . 1 | . . .
 . . . | . 2 . | . . .
 

 puzzle #17 (Ocean) 22 steps
 . . . | . 5 . | 2 4 1
 . . . | 9 . . | 6 . .
 . . . | . 7 1 | . . .
 ------+-------+------
 9 7 . | . . . | 3 6 .
 2 . . | . . . | . . 9
 . 1 6 | . . . | . 2 8
 ------+-------+------
 . . . | 7 1 . | . . .
 . . 4 | . . 3 | . . .
 5 9 7 | . 2 . | . . . 


 puzzle #18 (Ocean) 22 steps 
 7 . . | 3 . 8 | . 5 .
 . 9 . | . . . | . 2 .
 . . . | 5 . 9 | . . .
 ------+-------+------
 5 . . | . 6 . | 4 . 7
 . . . | 4 . 1 | . . .
 3 . 4 | . 7 . | . . 6
 ------+-------+------
 . . . | 7 . 4 | . . .
 . 3 . | . . . | . 9 .
 . 5 . | 2 . 6 | . . 8



 puzzle #19 (Ocean) 22 steps 
 7 . . | . 2 . | . . .
 . . . | 6 . . | 5 . 4
 . . . | 7 . . | 2 . .
 ------+-------+------
 . . . | 1 . 7 | 9 . .
 9 . . | . . . | . . 3
 . . 6 | 4 . 2 | . . .
 ------+-------+------
 . . 5 | . . 6 | . . .
 8 . 4 | . . 5 | . . .
 . . . | . 7 . | . . 8

puzzle #20 (vidarino) 26 steps
 . . 4 | . . 3 | . . 1
 7 . . | 6 . . | . . .
 . . 2 | 8 . . | . . .
 ------+-------+------
 3 . . | . 4 . | 8 5 .
 . 7 . | . . . | . 9 .
 . 2 8 | . 5 . | . . 3
 ------+-------+------
 . . . | . . 2 | 9 . .
 . . . | . . 6 | . . 7
 1 . . | 5 . . | 3 . . 

puzzle #21 (vidarino) 26 steps
 8 . . | . 3 . | . . .
 . 2 . | . . 5 | . . .
 . . 3 | 8 . . | . 9 2
 ------+-------+------
 4 . . | . 2 . | 1 . 8
 . . . | . 4 . | . . .
 7 . 9 | . 1 . | . . 5
 ------+-------+------
 9 7 . | . . 6 | 2 . .
 . . . | 7 . . | . 4 .
 . . . | . 8 . | . . 9

puzzle #22 (ab) 20 steps
 9 6 . | . . . | . 3 4
 2 . . | . . . | . . 6
 . . . | 4 7 . | . . .
 ------+-------+------
 . . 7 | 8 . . | . . .
 . . 8 | . 5 . | 3 . .
 . . . | . . 2 | 9 . .
 ------+-------+------
 . . . | . 9 3 | . . .
 4 . . | . . . | . . 8
 6 5 . | . . . | . 9 3
 

puzzle #23 (Tarek) 20 steps
 . . . | . 4 . | . 6 . 
 3 . . | 8 . . | 7 . . 
 . . 4 | . 5 . | 2 . . 
-------+-------+------
 . . 5 | . . . | . 8 . 
 1 . 2 | 5 . 4 | 6 . 3 
 . 6 . | . . . | 4 . . 
-------+-------+------
 . . 7 | . 9 . | 5 . . 
 . . 3 | . . 1 | . . 6 
 . 8 . | . 2 . | . . .

 puzzle #24 (Ocean) 25 steps 
 . . 1 | 2 3 4 | . . .
 . 5 . | 1 . . | . . .
 2 6 . | . . . | . . .
 ------+-------+------
 7 8 . | . . . | . 2 .
 . . 9 | 8 . 7 | 3 . .
 . 2 . | . . . | . 7 5
 ------+-------+------
 . . . | . . . | . 5 3
 . . . | . . 3 | . 8 .
 . . . | 9 8 5 | 4 . .


 puzzle #25 (Ocean) 23 steps
 . . . | 3 . . | 2 . .
 . . . | 8 . 7 | . . 4
 . . . | . 9 . | 6 . 5
 ------+-------+------
 9 3 . | . . . | 8 . .
 . 7 6 | . . . | 5 4 .
 . . 4 | . . . | . 3 2
 ------+-------+------
 2 . 5 | . 7 . | . . .
 1 . . | 4 . 5 | . . .
 . . 3 | . . 9 | . . .


puzzle #26 (Ocean) 21-steps
 9 . . | . . . | 5 4 2
 2 1 . | . . . | 9 . .
 . . 4 | . . . | . . 8
 ------+-------+------
 . . . | 8 4 1 | . . .
 . . . | . 2 . | . . .
 . . . | 3 7 6 | . . .
 ------+-------+------
 4 . . | . . . | 8 . .
 . . 7 | . . . | . 1 3
 6 2 8 | . . . | . . 7 

puzzle #27 (Ocean) 20-steps
 . . . | . . . | 1 . .
 4 . . | . . 8 | 7 3 .
 2 . 5 | 9 . . | . . .
 ------+-------+------
 5 . . | . . . | . 6 .
 . 8 . | . . . | . 2 .
 . 4 . | . . . | . . 5
 ------+-------+------
 . . . | . . 7 | 2 . 3
 . 5 6 | 4 . . | . . 1
 . . 3 | . . . | . . .
 

puzzle #28 (JPF) 20 steps
 . . . | . . 7 | 6 8 4
 . . . | 1 . 3 | . 9 .
 . . . | . 4 . | 1 . .
-------+-------+-------
 7 . 6 | . . 5 | . . 3
 . . . | . . . | . . .
 5 . . | 7 . . | 8 . 2
-------+-------+-------
 . . 1 | . 5 . | . . .
 . 7 . | 4 . 2 | . . .
 9 2 3 | 8 . . | . . .

puzzle #29 (JPF) 21 steps
 . . . | . 3 . | 6 . 8
 2 . . | . . 8 | 5 . .
 . . 9 | . . . | . . 1
-------+-------+-------
 . 5 . | . 2 . | 8 . .
 . 6 . | 4 . 3 | . 2 .
 . . 2 | . 8 . | . 6 .
-------+-------+-------
 1 . . | . . . | 7 . .
 . . 8 | 1 . . | . . 4
 7 . 4 | . 9 . | . . .


puzzle #30 (Ocean) 22 steps
 . . . | . 2 9 | . . 7
 . . . | 8 . 4 | . 6 5
 . . . | 1 . . | 2 8 9
 ------+-------+------
 . . 1 | . . . | . . 3
 . 9 . | . . . | . 2 .
 5 . . | . . . | 7 . .
 ------+-------+------
 9 3 7 | . . 1 | . . .
 4 1 . | 9 . 2 | . . .
 2 . . | 3 4 . | . . .

puzzle #31 (Ruud) 28 steps
 . . 5 | 9 . . | . . 8
 . . 1 | . . . | . . 5
 . . 2 | 3 . . | . . .
 ------+-------+------
 . . . | 4 . . | . 1 .
 . . 7 | . 3 . | 2 . .
 . 6 . | . . 1 | . . .
 ------+-------+------
 . . . | . . 9 | 4 . .
 9 . . | . . . | 7 . .
 8 . . | . . 5 | 3 . .


puzzle #32 (vidarino) 22 steps
 . 7 6 | 3 . . | . . .
 8 . . | . . 5 | . 6 .
 9 . . | . 7 . | 1 . .
 ------+-------+------
 . . . | . 5 8 | 2 . .
 . 2 . | . . . | . 8 .
 . . 7 | 9 3 . | . . .
 ------+-------+------
 . . 8 | . 9 . | . . 5
 . 6 . | 2 . . | . . 1
 . . . | . . 3 | 8 2 . 

puzzle #33 (JPF) 21 steps
 . 8 . | 2 . . | 9 . 1
 . . 4 | . 6 . | . 5 .
 . . . | . . 7 | . . 6
-------+-------+-------
 . 6 . | . . . | 5 . 8
 . . . | 8 . 5 | . . .
 3 . 8 | . . . | . 7 .
-------+-------+-------
 6 . . | 7 . . | . . .
 . 1 . | . 2 . | 6 . .
 8 . 9 | . . 1 | . 2 .

puzzle #34 (JPF) 20 steps
 . 8 . | . . 9 | . 6 .
 . . 5 | . . 4 | 2 . .
 . . . | 7 3 . | . 5 8
-------+-------+-------
 1 9 3 | . . . | . . .
 . . . | . . . | . . .
 . . . | . . . | 6 9 4
-------+-------+-------
 8 6 . | . 1 2 | . . .
 . . 4 | 9 . . | 7 . .
 . 2 . | 4 . . | . 1 .


puzzle #35 (JPF) 20 steps
 1 6 . | 4 . . | . . 5
 . 4 . | . 2 . | 7 . .
 . . 9 | . . 1 | . 4 .
-------+-------+-------
 . . 7 | . . . | . . 4
 . 5 . | . 8 . | . 1 .
 9 . . | . . . | 3 . .
-------+-------+-------
 . 2 . | 7 . . | 1 . .
 . . 3 | . 6 . | . 5 .
 4 . . | . . 3 | . 6 7

 
puzzle #36 (vidarino) 28 steps
 5 . . | 8 . . | . . 2
 . 2 . | . 6 . | 9 . .
 . 4 . | . . . | . 3 7
 ------+-------+------
 . . . | 1 . . | . . .
 . . 3 | 9 . 7 | 8 . .
 . . . | . . 8 | . . .
 ------+-------+------
 8 3 . | . . . | . 1 .
 . . 5 | . 4 . | . 9 .
 2 . . | . . 1 | . . 5 

puzzle #37 (Ocean) 20 steps
 . 4 . | . . . | . 7 .
 2 . . | . 3 . | . . 4
 . . . | 9 . 1 | . . .
 ------+-------+------
 . . 3 | . 6 . | 5 . .
 . 5 . | 8 . 9 | . 6 .
 . . 2 | . 7 . | 9 . .
 ------+-------+------
 . . . | 2 . 6 | . . .
 4 . . | . 1 . | . . 8
 . 6 . | . . . | . 3 .
 

puzzle #38 (Ocean) 23 steps
 . . . | . . . | . . .
 . . 2 | 1 . 3 | 7 . .
 . 8 9 | . . . | 3 4 .
 ------+-------+------
 . 1 . | . 8 . | . 6 .
 . . . | 6 . 7 | . . .
 . 3 . | . 4 . | . 2 .
 ------+-------+------
 . 4 6 | . . . | 9 3 .
 . . 5 | 7 . 6 | 4 . .
 . . . | . . . | . . .


puzzle #39 (Ocean) 20 steps
 . 4 . | . 5 . | . 8 .
 7 . . | . 3 . | . . 4
 . . 3 | 7 . 4 | 2 . .
 ------+-------+------
 . . 4 | . . . | 1 . .
 8 3 . | . . . | . 6 9
 . . 6 | . . . | 8 . .
 ------+-------+------
 . . 8 | 5 . 6 | 7 . .
 6 . . | . 1 . | . . 8
 . 1 . | . 2 . | . 5 .

puzzle #40 (ab) 20 steps
 . . . | 9 . 7 | 8 . 1
 . . . | . . . | . . .
 . . . | 5 . 1 | 7 . 9
 ------+-------+------
 4 . 2 | 8 . . | 6 . 7
 . . . | . . . | . . .
 3 . 5 | . . 9 | 1 . 8
 ------+-------+------
 5 . 4 | 6 . 2 | . . .
 . . . | . . . | . . .
 7 . 8 | 4 . 3 | . . .

puzzle #41 (Ruud) 26 steps
 . . . | . . . | . 1 2
 . . 7 | 2 . 6 | . . .
 . . . | 9 . . | 4 . 3
 ------+-------+------
 1 . 5 | . . . | 9 . .
 . . . | . 7 . | . . .
 . . 2 | . . . | 8 . 6
 ------+-------+------
 3 . 4 | . . 8 | . . .
 . . . | 4 . 9 | 1 . .
 6 9 . | . . . | . . .

puzzle #42 (Tarek) 22 steps
 . . . | . . . | . . 7 
 . 1 8 | 5 9 . | . . . 
 . 2 . | . 3 . | 9 5 . 
-------+-------+------
 . . 5 | 4 . . | . . . 
 3 . . | . 7 . | . . 4 
 . . . | . . 3 | 1 . . 
-------+-------+------
 . 6 7 | . 4 . | . 9 . 
 . . . | . 8 1 | 2 6 . 
 5 . . | . . . | . . . 

puzzle #43 (ab) 21 steps
 . . . | . . . | 1 . .
 . . . | . . 7 | 9 . .
 7 5 . | . 8 6 | . . .
 ------+-------+------
 . 3 4 | . . . | . . .
 . . 6 | . . . | 7 . .
 . . . | . . . | 8 6 .
 ------+-------+------
 . . . | 2 4 . | . 5 3
 . . 1 | 5 . . | . . .
 . . 2 | . . . | . . .
 

puzzle #44 (JPF) 22 steps
 . . 2 | . . . | . . 7
 6 . 4 | . . . | . 1 .
 . 3 . | . . 6 | 5 4 .
-------+-------+-------
 . . . | 8 . . | . . .
 8 . 1 | . 2 . | 9 . 4
 . . . | . . 9 | . . .
-------+-------+-------
 . 2 8 | 5 . . | . 3 .
 . 6 . | . . . | 7 . 9
 5 . . | . . . | 2 . .
 
puzzle #45 (JPF) 22 steps
 . 5 . | 9 3 . | . . 6
 . 8 9 | . . 2 | . 7 .
 4 . . | . 8 7 | . . .
-------+-------+-------
 . . . | . . . | . . 5
 . . 4 | 2 . 9 | 1 . .
 1 . . | . . . | . . .
-------+-------+-------
 . . . | 1 2 . | . . 4
 . 1 . | 4 . . | 6 5 .
 8 . . | . 9 5 | . 2 .
 
puzzle #46 (JPF) 25 steps
 . 9 . | . . . | 5 . .
 6 . 7 | . . . | 3 . 9
 . . . | . . 6 | . 8 7
-------+-------+-------
 . . . | 3 . . | 4 5 1
 . . . | 1 . 5 | . . .
 1 5 3 | . . 8 | . . .
-------+-------+-------
 7 1 . | 4 . . | . . .
 8 . 2 | . . . | 6 . 5
 . . 5 | . . . | . 7 .

puzzle #47 (Ocean) 20 steps
 . 9 . | . 5 . | . 1 .
 2 . . | . . . | . . 6
 . . . | 1 . 6 | . . .
-------+-------+------
 . . 8 | . 7 . | 2 . .
 7 . . | 6 . 1 | . . 3
 . . 3 | . 9 . | 4 . .
-------+-------+------
 . . . | 5 . 4 | . . .
 3 . . | . . . | . . 2
 . 5 . | . 6 . | . 7 . 

puzzle #48 (JPF) 24 steps
 . . 7 | . . 1 | . . .
 . 4 . | 5 . . | . . .
 8 6 . | . . . | . . 3
-------+-------+-------
 . . 2 | 1 . . | . . .
 . 3 1 | 8 . 2 | 6 9 .
 . . . | . . 7 | 1 . .
-------+-------+-------
 3 . . | . . . | . 4 5
 . . . | . . 8 | . 7 .
 . . . | 7 . . | 2 . .

puzzle #49 (ab) 20 steps
 . . . | . . . | . . .
 . . . | 6 2 3 | . . .
 . . 5 | . 4 . | 8 . .
 ------+-------+------
 . 7 . | . . . | . 3 .
 . 8 9 | . 5 . | 7 4 .
 . 3 . | . . . | . 2 .
 ------+-------+------
 . . 6 | . 8 . | 9 . .
 . . . | 4 7 2 | . . .
 . . . | . . . | . . .

puzzle #50 (Ocean) 24 steps
 . 5 . | . . . | . 2 .
 6 3 . | . 9 . | . 8 7
 . . . | 3 . 2 | . . .
-------+-------+------
 . . 1 | . . . | 6 . .
 . 9 . | . . . | . 5 .
 . . 4 | . . . | 8 . .
-------+-------+------
 . . . | 4 . 7 | . . .
 4 7 . | . 5 . | . 6 8
 . 2 . | . . . | . 9 .


puzzle #51 (Ocean/ab) 27 steps
 . 5 . | . . . | . 2 .
 6 3 . | . 9 . | . 8 4
 . . . | 3 . 2 | . . .
 ------+-------+------
 . . 1 | . . . | 6 . .
 . 9 . | . . . | . 5 .
 . . 4 | . . . | 8 . .
 ------+-------+------
 . . . | 4 . 7 | . . .
 4 7 . | . 5 . | . 6 8
 . 2 . | . . . | . 9 .

puzzle #52 (Tarek) 24 steps
 . . . | 8 9 5 | . . . 
 . . 9 | . . . | 7 . . 
 . 1 . | . . . | . 8 . 
-------+-------+------
 5 . . | . 2 . | . . 9 
 9 . . | 3 . 1 | . . 6 
 6 . . | . 8 . | . . 3 
-------+-------+------
 . 4 . | . . . | . 3 . 
 . . 7 | . . . | 4 . . 
 . . . | 4 6 7 | . . . 

puzzle #53 (Tarek) 20 steps
 . . . | 8 9 5 | . . . 
 . . 9 | . . . | 7 . . 
 . 1 . | . . . | . 8 . 
-------+-------+------
 5 . . | . 2 . | . . 9 
 9 . . | 3 . 1 | . . 6 
 6 . . | . 4 . | . . 3 
-------+-------+------
 . 4 . | . . . | . 3 . 
 . . 8 | . . . | 5 . . 
 . . . | 4 6 7 | . . .   

puzzle #54 (JPF) 21 steps
 7 . . | . . . | . . 6
 . 4 . | 3 . 9 | . 2 .
 . . . | . . . | . . .
-------+-------+-------
 . 2 . | . 9 . | . 5 .
 . . . | 4 7 1 | . . .
 . 9 . | . 6 . | . 3 .
-------+-------+-------
 . . . | . . . | . . .
 . 3 . | 5 . 7 | . 9 .
 8 . . | . . . | . . 1

puzzle #55 (Nick70) 21 steps
 1 . . | . 5 . | . . .
 . . . | 3 . . | . 2 .
 . . 9 | . . . | 4 . .
-------+-------+-------
 . 3 . | . . 4 | . . .
 2 . . | . 3 . | . . 8
 . . . | 9 . . | . 6 .
-------+-------+-------
 . . 4 | . . . | 1 . .
 . 6 . | . . 9 | . . .
 . . . | . 2 . | . . 7

puzzle #56 (JPF) 22 steps
 1 . . | . . . | . . 4
 . 5 . | 6 . 9 | . 8 .
 . . . | . . . | . . .
-------+-------+-------
 . 3 . | . 9 . | . 6 .
 . . . | 2 7 4 | . . .
 . 9 . | . 1 . | . 2 .
-------+-------+-------
 . . . | . . . | . . .
 . 6 . | 5 . 7 | . 9 .
 7 . . | . . . | . . 2

puzzle #57 (Ocean) 20 steps
 . . . | . . 1 | . . .
 . . . | . 7 . | 3 . 5
 . . . | 5 . . | 9 . .
 ------+-------+------
 . . 3 | 4 6 . | . . .
 . 4 . | 3 . 2 | 6 . .
 2 . . | . 1 . | . . 7
 ------+-------+------
 . 6 1 | . 5 . | . 9 .
 . . . | . . . | 2 . .
 . 5 . | . . 4 | . . .


puzzle #58 (Ocean) 22 steps
 . . . | . 1 . | . . .
 . . . | . . 2 | 1 . .
 . 3 1 | 4 . . | 5 . .
 ------+-------+------
 . 4 . | 6 . 7 | 3 . .
 8 . . | . . . | . . 4
 . . 2 | 5 . 4 | . 6 .
 ------+-------+------
 . . 4 | . . 9 | 2 7 .
 . . 8 | 3 . . | . . .
 . . . | . 2 . | . . .

puzzle #59 (Ocean) 28 steps
 . 1 . | 2 3 . | . . 4
 5 . . | 6 . . | 7 . .
 . . . | . . . | 8 3 .
 ------+-------+------
 3 2 . | . . . | . 1 .
 7 . . | . 2 . | . . 8
 . . . | . . . | . 4 .
 ------+-------+------
 . 8 9 | . . . | . . .
 . . 4 | 3 . 5 | . . .
 6 . . | . 4 . | . . .



puzzle #60 (ab) 20 steps
 . . . | . . . | . . .
 . 4 . | . . . | . 6 .
 . . 2 | 9 . 7 | 5 . .
 ------+-------+------
 . . 7 | . 6 . | 2 . .
 . . . | 5 3 8 | . . .
 . . 8 | . 4 . | 9 . .
 ------+-------+------
 . . 9 | 2 . 6 | 8 . .
 . 6 . | . . . | . 5 .
 . . . | . . . | . . .

puzzle #61 (Ocean) 21 steps
 . 9 . | . . . | . 7 .
 1 . . | . . . | . . 6
 . . 5 | 4 . 9 | 3 . .
 ------+-------+------
 . . 7 | . 8 . | 6 . .
 . . . | 5 . 6 | . . .
 . . 2 | . 9 . | 4 . .
 ------+-------+------
 . . 3 | 6 . 7 | 9 . .
 2 . . | . . . | . . 3
 . 5 . | . . . | . 1 .
 

puzzle #62 (Ocean) 25 steps
 . 1 . | . . 2 | . 3 .
 4 . . | . . . | 1 5 .
 . . . | . . 6 | . . .
 ------+-------+------
 . . . | . . . | . . 7
 . . . | . . 1 | 8 . .
 2 . 7 | . 8 . | . . .
 ------+-------+------
 . 3 . | . 4 . | . . .
 8 4 . | . . . | . . 6
 . . . | 5 . . | . 2 9   


puzzle #63 (Ocean) 23 steps.
 . . . | . . . | . . .
 . . 1 | . 2 . | . 3 .
 . 4 . | 5 6 . | 7 . .
 ------+-------+------
 . . 2 | . . . | . . .
 . 1 8 | . . . | . . .
 . . . | . . . | 4 6 5
 ------+-------+------
 . . 3 | . . 2 | . . .
 . 5 . | . . 9 | . . 3
 . . . | . . 8 | . 9 1 

puzzle #64 (Ocean) 26 steps
 . . . | . 1 . | . . .
 . . . | 2 3 4 | . . .
 . . 1 | . . . | 5 . .
 ------+-------+------
 . 2 . | . . . | . 6 .
 6 3 . | . . . | . 2 4
 . 4 . | . . . | . 7 .
 ------+-------+------
 . . 5 | . . . | 8 . .
 . . . | 9 6 7 | . . .
 . . . | . 4 . | . . .

puzzle #65 (ab) 22 steps
 . . . | . . . | . 5 .
 3 5 . | 7 . . | . . 2
 8 . 7 | . 2 . | . . .
 ------+-------+------
 . . . | . 6 . | . . .
 . 1 9 | . . 8 | 4 . .
 7 4 . | . . . | . 1 .
 ------+-------+------
 . . . | . 1 . | 3 . .
 . 3 . | 5 9 . | . 4 .
 . . . | 4 . . | 2 6 .


puzzle #66 (JPF) 23 steps
 1 . . | . . . | . 2 .
 . . . | 8 . . | . . .
 3 . 9 | 5 . . | 1 4 .
-------+-------+-------
 . . 3 | . . 1 | . 6 .
 . 5 . | 9 . 3 | . 8 .
 . 9 . | 4 . . | 2 . .
-------+-------+-------
 . 6 2 | . . 9 | 3 . 5
 . . . | . . 5 | . . .
 . 3 . | . . . | . . 2
 
puzzle #67 (Ocean) 23 steps
 . . . | . . . | . . .
 . . . | . 1 2 | . . 3
 4 . . | . . . | 5 6 .
 ------+-------+------
 . . . | . . 3 | . 1 2
 . . . | . 7 . | . . .
 8 5 . | 9 . . | . . .
 ------+-------+------
 . 2 3 | . . . | . . 6
 9 . . | 4 8 . | . . .
 . . . | . . . | . . .

puzzle #68 (Ocean/Red Ed) 25 steps
 . . . | . . . | . . .
 . . . | . 8 2 | . . 7
 4 . . | . . . | 5 6 .
 ------+-------+------
 . . . | . . 3 | . 1 2
 . . . | . 7 . | . . .
 8 5 . | 9 . . | . . .
 ------+-------+------
 . 2 3 | . . . | . . 6
 7 . . | 4 9 . | . . .
 . . . | . . . | . . .

puzzle #69 (Red Ed) 25 steps
 . 1 4 | . . . | 5 2 .
 2 . . | 5 . 1 | . . 7
 . . . | 4 . 2 | . . .
 ------+-------+------
 . . . | 3 . 8 | . . .
 . 3 7 | . . . | 1 8 .
 5 . . | . . . | . . 6
 ------+-------+------
 4 . . | . . . | . . 2
 1 . . | 6 . 5 | . . 8
 . 5 6 | . . . | 3 7 .

puzzle #70 (Red Ed) 20 steps
 . . . | . . . | . . .
 1 . . | 4 . 2 | . . 5
 5 . . | 7 . 3 | . . 2
 ------+-------+------
 . 1 8 | . . . | 9 7 .
 . 6 5 | . . . | 1 2 .
 . 2 7 | . . . | 4 5 .
 ------+-------+------
 7 . . | 9 . 6 | . . 1
 2 . . | 3 . 1 | . . 9
 . . . | . . . | . . .

puzzle #71 (Red Ed/ab) 24 steps
 . . . | . . . | . . .
 1 . . | 4 . 2 | . . 5
 5 . . | 7 . 3 | . . 2
 ------+-------+------
 . 1 8 | . . . | 9 7 .
 . 6 . | . . . | . 2 .
 . . 7 | . . . | 4 . .
 ------+-------+------
 7 . . | 9 . 6 | . . 1
 2 . . | 3 . 1 | . . 9
 . . . | . . . | . . .

puzzle #72 (Red Ed) 26 steps
 . . . | . . . | . . .
 1 . . | 4 . 2 | . . 5
 5 . . | 9 . 3 | . . 2
 ------+-------+------
 . 1 8 | . . . | 4 7 .
 . 6 . | . . . | . 2 .
 . . 7 | . . . | 9 . .
 ------+-------+------
 2 . . | 7 . 6 | . . 1
 6 . . | 3 . 1 | . . 9
 . . . | . . . | . . .

for some reason I missed out this one from Ocean
puzzle #73 (Ocean) 22 steps
 . . . | 9 . 6 | . . .
 . . 1 | . 3 . | 6 . .
 . 4 . | . 1 . | . 8 .
-------+-------+------
 4 . . | . . . | . . 2
 . 7 6 | . . . | 9 5 .
 5 . . | . . . | . . 8
-------+-------+------
 . 5 . | . 7 . | . 4 .
 . . 3 | . 9 . | 1 . .
 . . . | 3 . 8 | . . .

puzzle #74 (Ocean) 28 steps
 . . . | . . . | . 1 .
 . . 2 | . . . | . 3 4
 5 . . | . 2 6 | . . .
 ------+-------+------
 . . . | . 6 7 | . . .
 1 . . | . . . | . . 3
 . . . | 5 8 . | . . .
 ------+-------+------
 . . . | 4 1 . | . . 9
 2 7 . | . . . | 6 . .
 . 5 . | . . . | . . .

puzzle #75 (Ocean/Red Ed) 22 steps
 . 7 . | . . 8 | . 6 .
 9 3 . | . 4 . | . . 5
 . . . | 2 . . | . . .
 ------+-------+------
 . . 9 | 1 . . | . . 4
 . 2 . | . . . | . 3 .
 5 . . | . . 4 | 7 . .
 ------+-------+------
 . . . | . . 5 | . . .
 7 . . | . 8 . | . 9 6
 . 1 . | 7 . . | . 2 .

puzzle #76 (GSF/Red Ed) 21 steps
 . . . | . . . | . . .
 . 5 3 | 4 . 9 | 2 7 .
 7 . 9 | . . . | 1 . 3
 ------+-------+------
 . 3 . | 5 . 8 | . 1 .
 . . . | . . . | . . .
 . 6 . | 9 . 4 | . 2 .
 ------+-------+------
 2 . 8 | . . . | 7 . 1
 . 9 5 | 2 . 1 | 4 6 .
 . . . | . . . | . . .

puzzle #77 (Ocean) 23 steps
 . . . | . . . | . . 1
 . 2 3 | . . 4 | . . .
 . 5 . | . 6 1 | . . .
 ------+-------+------
 . . . | 7 . . | 8 3 .
 . . 5 | . . . | 6 . .
 . 9 4 | . . 2 | . . .
 ------+-------+------
 . . . | 2 5 . | . 4 .
 . . . | 8 . . | 7 2 .
 3 . . | . . . | . . .

puzzle #78 (Red Ed) 24 steps
 . 4 6 | . . . | 3 2 .
 . 1 . | 8 . 7 | . 9 .
 9 . . | . . . | . . 5
 ------+-------+------
 . . 9 | 7 . 2 | 8 . .
 . . . | . . . | . . .
 . . 3 | 9 . 6 | 2 . .
 ------+-------+------
 4 . . | . . . | . . 3
 . 7 . | 3 . 9 | . 1 .
 . 3 1 | . . . | 9 7 .

puzzle #79 (Red Ed) 22 steps
 8 7 . | . . 6 | . . 3
 . . 3 | 4 . . | . . 9
 . . . | 7 . . | . 4 .
 ------+-------+------
 5 . . | 8 . 4 | 9 1 .
 . . . | . 5 . | . . .
 . 8 1 | 6 . 3 | . . 4
 ------+-------+------
 . 6 . | . . 8 | . . .
 3 . . | . . 1 | 4 . .
 1 . . | 3 . . | . 9 6

puzzle #80 (JPF/Red Ed) 25 steps
 . . . | . . 1 | . . .
 6 . . | 9 . 7 | 3 . .
 . . 5 | . . . | . 8 .
 ------+-------+------
 . . . | . . 3 | . 4 8
 . . . | . . . | . . .
 3 2 7 | . . . | . 9 .
 ------+-------+------
 7 6 . | 5 . . | 2 . .
 9 . 3 | 7 . . | . . .
 . 1 4 | 8 . . | . 5 .

puzzle #81 (JPF) 22 steps
 . . . | . . 1 | . . .
 6 . . | 9 . 7 | 3 . .
 . . 9 | . . . | . 8 .
-------+-------+-------
 . . . | . . 2 | . 4 8
 . . . | . . . | . . .
 3 2 7 | . . . | . 9 .
-------+-------+-------
 9 6 . | 5 . . | 2 . .
 2 . 5 | 7 . . | . . .
 . 1 4 | 8 . . | . 5 .
 
puzzle #82 (JPF) 21 steps
 . . 9 | . 5 . | 7 . .
 4 . . | 3 . 7 | . . 8
 . . . | . . . | . . .
-------+-------+-------
 1 4 . | 9 . 6 | . 5 7
 . . . | . . . | . . .
 . 5 . | . 4 . | . 1 .
-------+-------+-------
 5 . . | . . . | . . 9
 9 . . | 8 . 3 | . . 1
 . 2 . | . 6 . | . 4 .

puzzle #83 (JPF) 20 steps
 . . 5 | . 2 1 | . 7 .
 1 . . | . 3 . | 5 . .
 . 3 . | . . 4 | . . 9
-------+-------+-------
 3 . 9 | . . . | . . .
 6 7 . | . . . | . 3 4
 . . . | . . . | 2 . 6
-------+-------+-------
 5 . . | 8 . . | . 4 .
 . . 3 | . 1 . | . . 5
 . 8 . | 2 6 . | 3 . .
 
puzzle #84 (Red Ed) 26 steps
 . . 2 | 8 . . | . . 7
 . . . | . 9 . | 2 4 .
 . . . | . . 5 | . 8 .
 ------+-------+------
 . 2 . | 9 . . | 6 . .
 9 4 . | . 1 . | . 2 .
 . 6 . | . . 7 | . . 9
 ------+-------+------
 . 1 . | . . . | . . 8
 7 . 6 | 5 8 1 | . . .
 . 8 . | . 4 . | . . .

puzzle #85 (JPF) 22 steps
 . 2 5 | . 3 . | 6 8 .
 7 . . | 8 . 1 | . . 9
 . . . | . 2 . | . . .
 ------+-------+------
 5 . 2 | . . . | 1 . 4
 3 . . | . . . | . . 7
 . 4 . | . . . | . 5 .
 ------+-------+------
 . 8 . | . . . | . 1 .
 2 6 . | . . . | . 4 3
 . . . | 3 9 2 | . . .

puzzle #86 (JPF) 20 steps
 . 9 . | 1 . 2 | . 5 .
 8 . . | . . . | . . 4
 5 . 7 | . . . | 9 . 2
-------+-------+-------
 . . . | 2 8 1 | . . .
 . . . | . . . | . . .
 . . . | 6 9 5 | . . .
-------+-------+-------
 1 . 2 | . . . | 3 . 5
 9 . . | . . . | . . 1
 . 6 . | 7 . 4 | . 2 .


puzzle #87 (JPF) 21 steps
 . 3 4 | 6 . . | 1 . .
 5 . . | . . . | . . .
 6 . 8 | . 9 3 | . . 2
-------+-------+-------
 3 . . | 7 . . | 8 . .
 . . 9 | . . . | 6 . .
 . . 2 | . . 8 | . . 7
-------+-------+-------
 8 . . | 3 1 . | 5 . 9
 . . . | . . . | . . 3
 . . 3 | . . 7 | 2 4 .

 
puzzle #88 (JPF) 23 steps
 6 . 9 | . . . | 3 . 1
 8 . . | 4 . 3 | . . 6
 . 3 . | . . . | . 5 .
-------+-------+-------
 . . . | . 5 . | . . .
 . . 1 | 8 . 6 | 9 . .
 . . 8 | . . . | 6 . .
-------+-------+-------
 1 9 . | . . . | . 2 3
 3 . . | . . . | . . 4
 . . . | 5 . 1 | . . .

puzzle #89 (gsf) 24 steps
 5 4 . | . 3 . | 7 . 1
 . . . | 1 . 2 | . . 8
 1 . . | . . . | . . .
 ------+-------+------
 . 8 . | . 6 . | . 3 .
 4 . . | 2 . 7 | . . 5
 . 2 . | . 4 . | . 9 .
 ------+-------+------
 . . . | . . . | . . 2
 2 . . | 8 . 6 | . . .
 8 . 4 | . 2 . | . 1 3

puzzle #90 (gsf) 22 steps
 . . . | 9 . 2 | . . .
 . 7 . | . . . | . 5 .
 . . 8 | 3 . 1 | 4 . .
 ------+-------+------
 7 . . | . . . | . . 1
 . 3 . | 4 . 6 | . 9 .
 6 . . | . . . | . . 4
 ------+-------+------
 . . 5 | 1 . 9 | 3 . .
 . 8 . | . . . | . 6 .
 . . . | 5 . 4 | . . .

puzzle #91 (Ocean) 24 steps
 . . . | 1 . . | . 2 .
 . . . | . . . | 3 . 4
 . . . | . 5 6 | . 7 .
 ------+-------+------
 8 . . | . 3 . | 9 . .
 . . 9 | 8 . 7 | 4 . .
 . . 2 | . 9 . | . . 1
 ------+-------+------
 . 6 . | 2 4 . | . . .
 1 . 8 | . . . | . . .
 . 7 . | . . 3 | . . .

puzzle #92 (Red Ed) 25 steps
 . . . | 4 5 . | 8 . .
 . 2 . | . . 3 | . 7 .
 5 . . | 2 . 8 | . . .
 ------+-------+------
 . 8 9 | . . . | 7 . 1
 1 . . | . . . | . . 9
 7 . 3 | . . . | 5 8 .
 ------+-------+------
 . . . | 7 . 5 | . . 6
 . 5 . | 6 . . | . 4 .
 . . 6 | . 1 4 | . . .

puzzle #93 (Red Ed) 25 steps
 . 5 . | 3 . 2 | . . .
 6 . . | . 7 9 | . . .
 . . 2 | . . . | 8 . .
 ------+-------+------
 2 . . | 4 . . | . 9 8
 . 8 . | . . . | . 5 .
 3 1 . | . . 6 | . . 7
 ------+-------+------
 . . 1 | . . . | 7 . .
 . . . | 5 4 . | . . 6
 . . . | 9 . 7 | . 8 .

puzzle #94 (gsf) 24 steps
 . 1 . | 4 . 5 | 9 . .
 2 . 9 | . . . | . . .
 . 6 . | . 1 2 | . . 7
 ------+-------+------
 5 . . | . . . | 6 . 3
 . . 3 | . . . | 4 . .
 8 . 2 | . . . | . . 9
 ------+-------+------
 9 . . | 3 7 . | . 5 .
 . . . | . . . | 7 . 4
 . . 6 | 8 . 4 | . 9 .

puzzle #95 (gsf) 23 steps
 . . 2 | 4 . . | 7 . 6
 . . . | . 2 . | . . 4
 . . . | . . 5 | . 9 .
 ------+-------+------
 . 1 9 | . . . | 8 . .
 7 8 . | 5 . . | . . .
 . 5 4 | . . . | 9 . .
 ------+-------+------
 . . . | . . 1 | . 6 .
 . . . | . 3 . | . . 8
 . . 7 | 6 . . | 1 . 2

puzzle #96 (Ocean) 21 steps
 1 . . | . . . | . . 2
 . 3 4 | 5 . . | . 6 .
 . . . | . . 6 | . 5 .
 ------+-------+------
 . . 6 | . 1 . | . 3 .
 . . . | 7 . 4 | . . .
 . 8 . | . 3 . | 2 . .
 ------+-------+------
 . 7 . | 8 . . | . . .
 . 5 . | . . 7 | 8 9 .
 8 . . | . . . | . . 4

puzzle #97 (Ocean) 24 steps
 1 2 . | . . . | . 3 4
 . . . | 4 . 3 | . . .
 . . 5 | . . . | 6 . .
 ------+-------+------
 4 . . | . 3 . | . . 1
 . . . | 2 . 7 | . . .
 8 . . | . 6 . | . . 9
 ------+-------+------
 . . 9 | . . . | 5 . .
 . . . | 7 . 1 | . . .
 6 3 . | . . . | . 8 7

puzzle #98 (Ocean) 22 steps
 1 . 2 | 3 . 4 | 5 . 6
 . . . | 6 . 7 | . . .
 . . . | . . . | . . .
 ------+-------+------
 . . . | 5 8 6 | . . .
 . . . | . . . | . . .
 . 5 8 | . . . | 1 9 .
 ------+-------+------
 . . 5 | . . . | 9 . .
 . 2 . | . 3 . | . 6 .
 . 3 . | 2 . 1 | . 8 .

puzzle #99 (Red Ed) 25 steps
 . . 7 | . . . | 2 . .
 . . . | 4 . 5 | . . .
 4 . . | . 6 . | . . 8
 ------+-------+------
 . 5 . | . 2 . | . 9 .
 . . 1 | 5 . 3 | 7 . .
 . 4 . | . 9 . | . 1 .
 ------+-------+------
 8 . . | . 1 . | . . 9
 . . . | 7 . 6 | . . .
 . . 2 | . . . | 6 . .

puzzle #100 (Ocean) 24 steps
 . . 1 | 2 . 3 | 4 . .
 . . . | . . . | . . .
 5 6 . | . . . | . 7 2
 ------+-------+------
 . 8 . | . . . | . 2 .
 . . . | 1 . 4 | . . .
 . . 7 | . . . | 6 . .
 ------+-------+------
 . 4 . | 9 . 1 | . 8 .
 8 . 3 | 4 . 5 | 9 . 7
 . . . | . . . | . . .




Ruud also posted a whopping 293 contenders.

Also worth a mention are two 27 step non-symmetric puzzles posted by JPF but taken from gfroyle's list of 17 clue puzzles,
one 29 step non-symmetric puzzle posted by Red Ed and adapted from a puzlle on gfroyle's list and one non-symmetric 30 step puzzle found by gsf on gfroyle's list of 18 clue puzzles:

Code: Select all

 

non-symmetric 27 step puzzle#1 (gfroyle):
 2 . . | . 6 . | 8 . .
 . . . | . . 1 | 3 . .
 . . . | . 7 5 | . . .
 ------+-------+------
 . 5 . | . . . | . 7 1
 . . 3 | 8 . . | . . .
 . . . | . . . | . . .
 ------+-------+------
 4 7 . | . . . | . 5 .
 . . . | 4 . . | 2 . .
 . . . | . . . | . . .


non-symmetric 27 step puzzle#2 (gfroyle): 
 . . . | . 8 . | 2 . .
 . 1 . | . . . | 5 . .
 . 3 . | . . . | . 4 .
 ------+-------+------
 . . . | 6 . 3 | 4 . .
 8 . . | . . . | . . .
 7 . . | . . . | . . .
 ------+-------+------
 . . . | 1 . . | . . 7
 . . . | . . . | . 8 9
 2 . . | . 6 . | . . .
 

non-symmetric 29 step puzzle (gfroyle/Red Ed)
 . 9 . | . 8 . | 2 . .
 . 1 . | . . . | 5 . .
 . 3 . | . . . | . 4 .
 ------+-------+------
 . . . | 6 . 3 | 4 . .
 8 . . | . . . | . . .
 5 . . | . . . | . . .
 ------+-------+------
 . . . | 1 . . | . . 7
 . . . | . . . | . 8 9
 9 . . | . 6 . | . . .

non-symmetric 30 step puzzle (gfroyle)
 . . . | . . 1 | . 7 .
 . . 6 | . . . | 4 . .
 5 . . | . . . | . . .
 ------+-------+------
 8 1 . | . . . | . 3 .
 . . . | 4 6 . | . . .
 . . . | . 2 . | . . .
 ------+-------+------
 . . 4 | . . . | 9 . 2
 3 7 . | 8 . . | . . .
 . 9 . | . . . | . . .

non-symmetric 39 step puzzle (Tarek)
 . . 5 | 7 . . | . . .
 . 1 . | 9 3 . | 7 . .
 . . 6 | . . . | . . 4
-------+-------+------
 . . 8 | . . . | . 5 .
 . . . | . 9 . | . . .
 . 5 . | . 7 . | . . 2
-------+-------+------
 . 3 . | . . . | . 4 .
 . 8 7 | . . . | . . .
 . 4 . | . 6 8 | 3 1 .


[Ruud]

Hi ab,

Please help me understand what kind of puzzles you want in this thread.

A puzzle that can be solved with singles only does not require other techniques, so it would be silly to apply them.

Also, such a puzzle requires 81 - (#clues) steps. So posting a 17 with symmetry (there were 10 posted in another thread) would give the highest number of steps.

Or am I missing something?

Ruud.

[ab]

i want puzzles which take many steps, ie there are only a few possibilities at each stage. So a 17 might not qualify if you could place 8 clues at each stage, but a 28 might qualify if you could only place 3 clues at each stage. Maybe it's a dumb idea

[vidarino]

I think this was an interesting twist on puzzle creation.

I have long been a supporter of the "the narrower the solution path, the harder the puzzle" idea, but I never got around to actually trying to measure the breath of said path, until now.

Computer solvers will find these terribly simple, of course, but human solvers just might have to look hard to spot the next single, as there aren't that many around for each step.

Here are a couple of "narrow" puzzles, none requiring more than singles and locked candidates;

(Edit: I have removed these, since they weren't very good after all. Look below for some real ones.)

Vidar

[tarek]

ab,

I like the idea of only sigles puzzles.....

But I'm still not getting exactly what is it that you want in them....

Vidar seems to have guessed it, I'm still in the dark though.

Is it the number of cycles you're after

Tarek

[vidarino]

I'm guessing that ab is looking for puzzles that have as few as possible singles at any given time.

The Holy Grail of these puzzles would be one that has only one single opening move, which in turn reveals another single, etc., all the way until the inevitable avalanche of singles in the end.

[tarek]

hmmmmmmmmm....

Step=Cycle (or loop)...A cycle may have several singles at one time.

Now if we have 2 puzzles with the same number of steps, would the one having more Hidden singles be EASIER? (I suppose so...)

So:
1. Max number of steps
2. Fewest Hidden singles (visible & not required)...

In this case the solver/generator should look for Hidden singles first & after each single elimination (naked or hidden)...or should I leave it to chech for hidden singles first only.....

I'll try both & post puzzles representing both to compare.......

Tarek

[vidarino]

Now if we have 2 puzzles with the same number of steps, would the one having more Hidden singles be EASIER? (I suppose so...)

I just had that exact realization myself, and when looking for hidden singles first, a few of the puzzles I posted aren't so "narrow" after all. Oh well. I'll post some better ones in a bit. (I'm pondering merging the naked and hidden singles check into one, actually.)

Vidar

[vidarino]

OK, here's one that should be a lot stricter than the earlier ones I posted;

Code: Select all

+-------+-------+-------+
| . 2 . | . . 9 | . 7 4 |
| . 3 . | 7 . . | . . 1 |
| 5 . . | . . 1 | . . 2 |
+-------+-------+-------+
| . . 8 | 3 . . | . 6 . |
| . . . | . . . | . . . |
| . 6 . | . . 5 | 1 . . |
+-------+-------+-------+
| 3 . . | 5 . . | . . 7 |
| 2 . . | . . 3 | . 9 . |
| 1 4 . | 2 . . | . 5 . |
+-------+-------+-------+

Edit: one more

Code: Select all

+-------+-------+-------+
| 5 . . | . 9 . | . . . |
| . 7 8 | . 1 . | . . . |
| 9 4 . | 3 . . | . 1 . |
+-------+-------+-------+
| . . . | . . 7 | . 6 1 |
| 6 . 7 | . . . | 9 . 2 |
| 1 8 . | 6 . . | . . . |
+-------+-------+-------+
| . 2 . | . . 3 | . 4 7 |
| . . . | . 4 . | 5 2 . |
| . . . | . 8 . | . . 6 |
+-------+-------+-------+

[Ruud]

Narrow solving path. OK, understood.

This is my entry:

Code: Select all

3 . 5|. . .|6 . .
. 6 .|. . .|. . 2
. . .|. 9 .|1 7 .
-----+-----+-----
. . 4|3 . .|. . .
8 . .|. 2 .|. . 5
. . .|. . 9|3 . .
-----+-----+-----
. 5 6|. 1 .|. . .
9 . .|. . .|. 4 .
. . 3|. . .|9 . 8

It has 14 steps with 0 alternatives, 10 with only 1 alternative, including the opener.

Ruud.

[tarek]

So is this a diffcult one (Narrow one)? (I'm really not sure )

Code: Select all

Tarek #01
 . . . | . 2 . | . 9 . 
 . . 8 | 9 . 1 | 7 . 6 
 . 3 . | 6 . . | . 5 . 
-------+-------+------
 . 1 6 | . . . | . 8 . 
 3 . . | . . . | . . 9 
 . 8 . | . . . | 4 7 . 
-------+-------+------
 . 2 . | . . 3 | . 1 . 
 4 . 3 | 2 . 5 | 8 . . 
 . 7 . | . 6 . | . . . 

Tarek

[vidarino]

Allrighty, I have edited out my failed attempts at the top and instead submit these;

(Edit: removed. needed locked candidates.)

[vidarino]

So is this a diffcult one (Narrow one)? (I'm really not sure )

Not bad, but not quite as bad as the others here (save mine (now removed) from earlier). It opens with 3 possible singles, and after all those are entered, there are 4 more, then 2 more, then 3 more, ...

Compare to Ruud's (nice one, Ruud!), which opens with 2 singles, then no less than 13 consecutive one-single steps! That's going to be hard to beat.

By the way, ab, are locked candidates (box/line interaction) allowed? A few of mine need that, but since you started the thread you make the rules. I'll yank them out if not.

Vidar

[tarek]

Compare to Ruud's (nice one, Ruud!), which opens with 2 singles, then no less than 13 consecutive one-single steps! That's going to be hard to beat.

Now this part i need to understand.....

you need no less than 20 steps to solve the puzzle I posted, I consider that more difficult than 13 one single steps then 3 steps to solve it completely.....

Puzzled

Tarek

[vidarino]

you need no less than 20 steps to solve the puzzle I posted, I consider that more difficult than 13 one single steps then 3 steps to solve it completely.....

Sorry, I was a bit unclear. Ruud's puzzle has indeed got 13 one-single steps, but there are more steps afterwards.

My solver, which I have tweaked a bit to fit this purpose, solved yours in 14 steps (where each number indicating the number of available singles);
3,4,2,3,1,4,4,5,7,8,4,3,4,3

Ruud's puzzle took 30 steps;
2,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,1,1,1,4,1,2,3,2,6,7,9,2

Of course, no two solvers are identical, so there could be things I have overlooked, but I don't think I'm too far off.

Vidar