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

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.

Naked Single Explanation
Hidden Single Explanation
Locked Candidates Explanation
Full House Explanation
Try To Solve This Puzzle

Solution Steps:

  1. Locked Candidates Type 1 (Pointing): 6 in b4 => r1c1<>6
  2. Skyscraper: 8 in r3c9,r9c8 (connected by r39c1) => r12c8,r7c9<>8
  3. Skyscraper: 3 in r1c1,r2c7 (connected by r6c17) => r1c8,r2c23<>3
  4. W-Wing: 1/7 in r4c9,r8c8 connected by 7 in r1c89 => r4c8,r7c9<>1
  5. XY-Wing: 2/7/1 in r39c7,r8c8 => r2c8,r7c7<>1
  6. Uniqueness Test 4: 2/6 in r1c25,r2c25 => r12c2<>2
  7. Sue de Coq: r2c789 - {12348} (r2c6 - {48}, r3c7 - {12}) => r1c89,r3c9<>2, r3c9<>1, r2c3<>8
  8. Empty Rectangle: 2 in b7 (r3c27) => r7c7<>2
  9. Row 7 / Column 7 → 4 (Naked Single)
  10. Row 5 / Column 9 → 4 (Hidden Single)
  11. Locked Candidates Type 1 (Pointing): 5 in b6 => r6c13<>5
  12. Discontinuous Nice Loop: 3/9 r1c2 =6= r1c5 =2= r1c3 =8= r7c3 -8- r9c1 -5- r5c1 =5= r5c3 -5- r2c3 =5= r2c2 =6= r1c2 => r1c2<>3, r1c2<>9
  13. Row 1 / Column 2 → 6 (Naked Single)
  14. Row 1 / Column 5 → 2 (Naked Single)
  15. Row 2 / Column 5 → 6 (Full House)
  16. AIC: 7 7- r1c8 -4- r1c6 -8- r1c3 =8= r7c3 =2= r2c3 -2- r3c2 =2= r3c7 -2- r9c7 -7 => r89c8<>7
  17. Row 8 / Column 8 → 1 (Naked Single)
  18. Row 9 / Column 7 → 7 (Hidden Single)
  19. Naked Pair: 3,7 in r68c3 => r14c3<>3, r4c3<>7
  20. Row 1 / Column 1 → 3 (Hidden Single)
  21. Row 6 / Column 1 → 6 (Naked Single)
  22. Row 5 / Column 7 → 6 (Hidden Single)
  23. Row 4 / Column 9 → 1 (Hidden Single)
  24. Row 4 / Column 3 → 9 (Naked Single)
  25. Row 1 / Column 3 → 8 (Naked Single)
  26. Row 1 / Column 6 → 4 (Naked Single)
  27. Row 2 / Column 6 → 8 (Full House)
  28. Row 1 / Column 8 → 7 (Naked Single)
  29. Row 1 / Column 9 → 9 (Full House)
  30. Row 2 / Column 9 → 2 (Naked Single)
  31. Row 4 / Column 8 → 3 (Naked Single)
  32. Row 4 / Column 2 → 7 (Full House)
  33. Row 3 / Column 9 → 8 (Naked Single)
  34. Row 3 / Column 7 → 1 (Naked Single)
  35. Row 7 / Column 9 → 5 (Naked Single)
  36. Row 6 / Column 9 → 7 (Full House)
  37. Row 2 / Column 8 → 4 (Naked Single)
  38. Row 2 / Column 7 → 3 (Full House)
  39. Row 6 / Column 7 → 2 (Full House)
  40. Row 6 / Column 8 → 5 (Full House)
  41. Row 6 / Column 3 → 3 (Full House)
  42. Row 8 / Column 2 → 3 (Naked Single)
  43. Row 8 / Column 3 → 7 (Full House)
  44. Row 3 / Column 1 → 9 (Naked Single)
  45. Row 3 / Column 2 → 2 (Full House)
  46. Row 9 / Column 2 → 5 (Naked Single)
  47. Row 2 / Column 2 → 1 (Naked Single)
  48. Row 2 / Column 3 → 5 (Full House)
  49. Row 7 / Column 2 → 9 (Full House)
  50. Row 9 / Column 1 → 8 (Naked Single)
  51. Row 9 / Column 8 → 2 (Full House)
  52. Row 7 / Column 8 → 8 (Full House)
  53. Row 5 / Column 3 → 1 (Naked Single)
  54. Row 5 / Column 1 → 5 (Full House)
  55. Row 7 / Column 1 → 1 (Full House)
  56. Row 7 / Column 3 → 2 (Full House)
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