Perfect-18-1
the puzzle is in 3-template but it takes a lot to solve it, there is certainly a path with a number of three combinations shorter than the two orders that i currently use: the lexical order and an order based on a estimated number of templates per combination, but my implementation is too slow to try them all.
what is remarkable with this puzzle is the number of possible templates for a value at the beginning, 5894 for value 9, i don't remember having seen such a number for a puzzle with an unique solution,
but by experimenting, i know that the amount of possible templates at the beginning is not a characteristic of difficult puzzles only and this puzzle is another example
templates and candidates are correlated as i try to show in another post:
for each value consider two sets of cells, the set in which the value is set, the Value Cells and the set in which the value is a candidate, the Candidate Cells, for each value to compute the templates consists in organizing the candidate cells into subsets of (9-#VC) pairwise disconnected cells, the Complementary Sets, one template is the Value Cells + one Complementary Set.
the difficulty with this puzzle is to find a 'short' solution, as it has no 1-antibackdoor it needs a least two eliminations and indeed it has 12 2-antibackdoor, it remains to find a logical way to use them:
n4r7c2 with anyone of (n2r2c2 n6r2c7 n3r3c9 n6r4c4 n2r5c1 n6r5c8 n3r6c2 n7r6c6 n2r6c7 n3r8c1 n5r9c3 n3r9c7)
as for my other car, i have a whole bunch
http://clhs.lisp.se/Body/f_car_c.htm#car- Code: Select all
.....1..2..3....4..5..6.........2.3..7....8..6..4........3..5....2.7....1.......6
#VT: (56 5 5 64 59 6 70 677 5894)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil (14 76) (41) nil nil nil nil nil nil
2
#VT: (33 4 4 45 53 5 53 575 4668)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil (53) (65) nil nil (7) nil nil nil
2
#VT: (33 4 4 45 53 5 53 571 4569)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil nil nil nil nil nil nil nil nil
2 3
#VT: (5 4 4 25 30 4 29 282 1615)
Cells: (21 29) nil nil nil nil nil nil nil nil
SetVC: ( n1r3c3 n1r4c2 )
#VT: (9 4 4 25 30 4 29 282 1615)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil nil nil (37 69 79) (5 31 37 44 51) (42 67) (24 79) (5 11 24 47) (5 11 24 37 44 47 79)
2
#VT: (6 4 4 18 30 4 27 200 1144)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:(71 72) nil nil (60) nil nil nil nil nil
2
#VT: (6 4 4 18 30 4 27 200 1127)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil nil nil nil nil nil nil nil nil
2 3
#VT: (4 3 4 17 27 4 21 147 748)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:(44 63) (80) nil nil nil nil (18 53) nil nil
2
#VT: (4 3 4 17 27 4 21 140 744)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil nil nil nil nil nil nil nil nil
2 3
#VT: (4 3 4 8 23 4 14 113 535)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil nil nil (57 59 64 72 74 75) nil nil (62) (59 62) (59 62)
2
#VT: (4 3 3 8 23 4 14 110 492)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil nil (70) nil nil nil nil nil nil
2
#VT: (4 3 3 8 23 4 14 110 484)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil nil nil nil nil nil nil nil nil
2 3
#VT: (4 2 2 8 22 4 14 83 356)
Cells: nil (44 47 59 79) (37 72 74) nil nil nil nil nil nil
SetVC: ( n3r5c1 n2r5c8 n2r6c2 n2r7c5 n1r7c8 n3r8c9
n3r9c2 n2r9c7 n6r2c2 n1r8c4 n6r8c6 n6r4c7
n6r5c4 n6r7c3 n6r1c8 n4r8c7 n5r6c8 n5r8c1
n5r2c9 n5r1c4 n1r2c7 )
#VT: (2 2 2 7 3 1 14 83 356)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil nil nil nil nil nil nil nil nil
2
#VT: (2 2 2 6 3 1 4 19 77)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil nil nil nil nil nil (7 10 19 22) (10 19 22 75) nil
2
#VT: (2 2 2 6 3 1 4 17 47)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil nil nil nil nil nil nil nil nil
2 3
#VT: (2 2 2 4 3 1 2 3 7)
Cells: nil nil nil nil nil nil (15 31 52) nil nil
SetVC: ( n7r2c6 n7r4c4 n7r6c7 )
#VT: (2 2 2 4 3 1 2 3 7)
Cells: nil nil nil nil nil nil nil nil nil
Candidates:nil nil nil (1) nil nil nil (32 48 56 77 78) (1 3 25 26 51 55 63 77 78)
EraseCC: ( n3r3c7 n9r6c3 n1r6c9 n7r9c3 n9r1c7 n4r3c6
n5r9c6 n3r1c5 n9r5c6 n4r5c9 n8r6c5 n3r6c6
n8r7c6 n7r7c9 n9r9c4 n4r9c5 n8r9c8 n9r2c5
n2r3c4 n7r3c8 n8r3c9 n5r4c5 n9r4c9 n5r5c3
n1r5c5 n4r7c1 n9r7c2 n8r8c2 n9r8c8 n4r1c2
n8r1c3 n2r2c1 n8r2c4 n9r3c1 n8r4c1 n4r4c3
n7r1c1 )
7 4 8 5 3 1 9 6 2
2 6 3 8 9 7 1 4 5
9 5 1 2 6 4 3 7 8
8 1 4 7 5 2 6 3 9
3 7 5 6 1 9 8 2 4
6 2 9 4 8 3 7 5 1
4 9 6 3 2 8 5 1 7
5 8 2 1 7 6 4 9 3
1 3 7 9 4 5 2 8 6