The easy one needs only one XY-wing (next to basics, which a did not spot with pencil & paper)
The hard one can be solved without forcing chains but with 7 bivalue XY-chains:
- Code: Select all
[1,0] Pointing, Claiming | (6)r1,b1 => (-6)r3c1 (-6)r3c3 | (3)r1,b3 => (-3)r2c8 (-3)r2c9 | (4)b8,r7 => (-4)r7c7 (-4)r7c9 | (8)b8,r7 => (-8)r7c1 (-8)r7c3 | (7)b8,r8 => (-7)r8c8 | (4)c1,b1 => (-4)r2c2 | (5)c1,b7 => (-5)r8c2 (-5)r9c2 | (5)b6,c7 => (-5)r7c7 (-5)r9c7 | (6)b6,c8 => (-6)r8c8 (-6)r9c8 | (8)b6,c8 => (-8)r2c8 | (2)b7,/ => (-2)r1c9 (-2)r2c8 (-2)r3c7 (-2)r5c5 | (1)b9,\ => (-1)r1c1 (-1)r2c2 (-1)r3c3 (-1)r4c4 (-1)r5c5
[2,1] r1c9=3 Naked Single
[3,2] r9c3=3 Hidden Single in col 3
[4,2] Naked/Hidden Pairs,Triplets,Quads | NPair (47)r9c78 => (-4)r9c9 | NTriple (256)c9r789 => (-2)r2c9 (-2)r3c9 | NQuin (24567)b9e36789 => (-2)r7c7 (-2)r8c8 | NPair (13)\78 => (-3)r4c4 (-3)r6c6
[5,2] Naked/Hidden Pairs,Triplets,Quads | NPair (48)b3e69 => (-4)r2c8 (-4)r3c7
[6,2] Pointing, Claiming | (2)b3,r1 => (-2)r1c2 (-2)r1c3 | (3)b5,c5 => (-3)r2c5 (-3)r7c5 (-3)r8c5 | (2)b1,\ => (-2)r6c6 | (4)\,b5 => (-4)r4c5 (-4)r4c6 (-4)r5c6 (-4)r6c5 | (4)/,b5 => (-4)r6c6
[7,3] r7c6=4 Hidden Single in col 6
[7,4] r5c5=4 Hidden Single in box 5
[8,4] Naked/Hidden Pairs,Triplets,Quads | NQuin (13569)\16789 => (-9)r2c2 (-9)r3c3 (-56)r4c4
[9,4] Generalized Intersection | (7)\,r3,c4 => (-7)r3c4
[10,4] 2-String Kite (9)r1c7=r3c7-r8c2=r8c1 => (-9)r1c1
[11,5] r1c1=6 Naked Single
[11,6] r9c9=5 Naked Single
[12,7] r6c6=9 Naked Single
[12,8] r9c1=8 Naked Single
[12,9] r9c2=6 Naked Single
[13,9] Naked/Hidden Pairs,Triplets,Quads | NQuad (1479)b1e2347 => (-7)r3c3 | NQuin (12489)b1e24579 => (-19)r1c3 | NQuin (12678)c3r13467 => (-168)r5c3 | 1 (9)b4e6 => (-9)r5c2 | NPair (28)\23 => (-8)r4c4 | NQuad (1279)/2378 => (-7)r4c6
[14,10] r1c3=7 Naked Single
[14,11] r4c4=7 Naked Single
[14,12] r5c3=9 Naked Single
[15,12] Naked/Hidden Pairs,Triplets,Quads | NTriple (256)b5e367 => (-6)r4c5 (-56)r5c4 (-26)r6c5 | NPair (56)b5e37 => (-56)r5c6 | 1 (2)c6r5 => (-2)r2c6 (-2)r3c6
[16,13] r5c6=2 Naked Single
[16,14] r5c7=5 Naked Single
[17,15] r5c8=6 Hidden Single in row 5
[18,15] Naked/Hidden Pairs,Triplets,Quads | NQuad (1289)c2r1258 => (-18)r4c2 (-8)r6c2
[19,15] XY-wing [3] (3)(3=7)r2c6-(7=1)r2c8-(1=3)r8c8 => (-3)r8c6
[20,16] r2c6=3 Hidden Single in col 6
[21,16] XY-chain [4] (9)(9=1)r1c2-(1=8)r5c2-(8=1)r5c4-(1=9)r2c4 => (-9)r2c1
[22,17] r2c4=9 Hidden Single in row 2
[23,17] XY-chain [5] (3)(3=8)r6c5-(8=6)r7c5-(6=2)r7c9-(2=1)r7c3-(1=3)r7c7 => (-3)r6c7
[24,17] XY-chain [5] (5)(5=6)r6c4-(6=8)r6c3-(8=2)r3c3-(2=1)r7c3-(1=5)r7c1 => (-5)r7c4
[25,18] r7c1=5 Hidden Single in row 7
[26,18] Generalized Intersection | (1)r7,c7,/ => (-1)r3c7
[27,18] XY-chain [6] (9)(9=1)r1c2-(1=8)r5c2-(8=1)r5c4-(1=6)r3c4-(6=7)r3c6-(7=9)r3c7 => (-9)r1c7 (-9)r8c2 (-9)r3c1
[28,19] r1c2=9 Hidden Single in row 1
[28,20] r3c7=9 Hidden Single in row 3
[28,21] r8c1=9 Hidden Single in row 8
[28,22] r9c7=7 Hidden Single in col 7
[28,23] r2c8=7 Hidden Single in col 8
[28,24] r9c8=4 Hidden Single in box 9
[29,24] XY-chain [5] (6)(6=1)r3c4-(1=8)r5c4-(8=1)r5c2-(1=2)r8c2-(2=6)r8c9 => (-6)r8c4
[30,24] XY-chain [5] (1)(1=8)r5c2-(8=6)r6c3-(6=5)r6c4-(5=3)r8c4-(3=1)r8c8 => (-1)r8c2
[31,25] r8c2=2 Naked Single
[31,26] r8c9=6 Naked Single
[32,27] r2c2=8 Naked Single
[32,28] r2c9=4 Naked Single
[32,29] r3c3=2 Naked Single
[32,30] r3c9=8 Naked Single
[32,31] r5c2=1 Naked Single
[32,32] r5c4=8 Naked Single
[32,33] r6c5=3 Naked Single
[32,34] r7c3=1 Naked Single
[32,35] r7c7=3 Naked Single
[32,36] r7c9=2 Naked Single
[32,37] r8c5=7 Naked Single
[32,38] r8c6=5 Naked Single
[32,39] r8c8=1 Naked Single
[33,40] r1c8=2 Naked Single
[33,41] r2c1=1 Naked Single
[33,42] r2c5=2 Naked Single
[33,43] r3c1=4 Naked Single
[33,44] r4c5=1 Naked Single
[33,45] r4c6=6 Naked Single
[33,46] r4c7=4 Naked Single
[33,47] r6c4=5 Naked Single
[33,48] r6c7=2 Naked Single
[33,49] r6c8=8 Naked Single
[33,50] r7c4=6 Naked Single
[33,51] r7c5=8 Naked Single
[33,52] r8c4=3 Naked Single
[34,53] r1c7=1 Naked Single
[34,54] r3c4=1 Naked Single
[34,55] r3c5=6 Naked Single
[34,56] r3c6=7 Naked Single
[34,57] r4c2=5 Naked Single
[34,58] r4c3=8 Naked Single
[34,59] r4c8=3 Naked Single
[34,60] r6c2=4 Naked Single
[34,61] r6c3=6 Naked Single