3
8
5
1
9
7
4
2
6
1
2
4
7
2
7
5
2
9
1
3
6
4
8
3
1
8
7
3
5
6
4
9
1
2
5
7
6

This Sudoku Puzzle has 56 steps and it is solved using Locked Candidates Type 1 (Pointing), Skyscraper, undefined, Uniqueness Test 4, Sue de Coq, Empty Rectangle, Naked Single, Hidden Single, Discontinuous Nice Loop, Full House, AIC, Naked Pair techniques.

Try To Solve This Puzzle

Solution Steps:

  1. Locked Candidates Type 1 (Pointing): 2 in b6 => r8c8<>2
  2. Skyscraper: 3 in r2c5,r7c6 (connected by r27c8) => r3c6,r89c5<>3
  3. Skyscraper: 4 in r8c8,r9c4 (connected by r5c48) => r8c5,r9c79<>4
  4. W-Wing: 9/6 in r1c5,r4c6 connected by 6 in r8c56 => r3c6,r4c5<>9
  5. XY-Wing: 6/8/9 in r1c5,r27c4 => r3c4,r9c5<>9
  6. Uniqueness Test 4: 2/8 in r8c19,r9c19 => r89c9<>8
  7. Sue de Coq: r9c456 - {34789} (r9c2 - {37}, r7c4 - {89}) => r78c6,r8c5<>8, r7c6<>9, r9c7<>3
  8. Empty Rectangle: 8 in b3 (r7c49) => r3c4<>8
  9. Row 3 / Column 4 → 7 (Naked Single)
  10. Row 6 / Column 6 → 7 (Hidden Single)
  11. Locked Candidates Type 1 (Pointing): 5 in b5 => r5c78<>5
  12. Discontinuous Nice Loop: 1/4 r8c9 =2= r8c1 =8= r8c7 =3= r3c7 -3- r2c8 -5- r6c8 =5= r6c7 -5- r9c7 =5= r9c9 =2= r8c9 => r8c9<>1, r8c9<>4
  13. Row 8 / Column 9 → 2 (Naked Single)
  14. Row 8 / Column 1 → 8 (Naked Single)
  15. Row 9 / Column 1 → 2 (Full House)
  16. AIC: 6 6- r2c4 -8- r7c4 =8= r7c9 -8- r9c7 =8= r3c7 =3= r8c7 -3- r8c2 -7- r8c5 -6 => r12c5<>6
  17. Row 1 / Column 5 → 9 (Naked Single)
  18. Row 2 / Column 4 → 6 (Hidden Single)
  19. Naked Pair: 4,6 in r15c7 => r48c7<>4, r4c7<>6
  20. Row 8 / Column 8 → 4 (Hidden Single)
  21. Row 5 / Column 8 → 2 (Naked Single)
  22. Row 6 / Column 4 → 2 (Hidden Single)
  23. Row 4 / Column 6 → 9 (Hidden Single)
  24. Row 4 / Column 7 → 1 (Naked Single)
  25. Row 8 / Column 7 → 3 (Naked Single)
  26. Row 8 / Column 2 → 7 (Naked Single)
  27. Row 9 / Column 2 → 3 (Full House)
  28. Row 8 / Column 5 → 6 (Naked Single)
  29. Row 8 / Column 6 → 1 (Full House)
  30. Row 9 / Column 6 → 8 (Naked Single)
  31. Row 4 / Column 5 → 4 (Naked Single)
  32. Row 4 / Column 9 → 6 (Full House)
  33. Row 7 / Column 6 → 3 (Naked Single)
  34. Row 3 / Column 6 → 5 (Naked Single)
  35. Row 5 / Column 6 → 6 (Full House)
  36. Row 7 / Column 4 → 9 (Naked Single)
  37. Row 5 / Column 4 → 8 (Naked Single)
  38. Row 9 / Column 4 → 4 (Full House)
  39. Row 9 / Column 5 → 7 (Full House)
  40. Row 5 / Column 5 → 5 (Full House)
  41. Row 5 / Column 7 → 4 (Full House)
  42. Row 1 / Column 9 → 4 (Naked Single)
  43. Row 1 / Column 7 → 6 (Full House)
  44. Row 7 / Column 8 → 1 (Naked Single)
  45. Row 7 / Column 9 → 8 (Full House)
  46. Row 2 / Column 9 → 5 (Naked Single)
  47. Row 2 / Column 8 → 3 (Naked Single)
  48. Row 2 / Column 5 → 8 (Full House)
  49. Row 3 / Column 5 → 3 (Full House)
  50. Row 9 / Column 9 → 9 (Naked Single)
  51. Row 3 / Column 9 → 1 (Full House)
  52. Row 9 / Column 7 → 5 (Full House)
  53. Row 3 / Column 8 → 9 (Naked Single)
  54. Row 3 / Column 7 → 8 (Full House)
  55. Row 6 / Column 7 → 9 (Full House)
  56. Row 6 / Column 8 → 5 (Full House)
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