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

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, AIC, Full House, 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): 9 in b3 => r8c9<>9
  2. Skyscraper: 1 in r6c1,r9c2 (connected by r69c9) => r4c2,r78c1<>1
  3. Skyscraper: 5 in r7c3,r8c9 (connected by r3c39) => r7c78,r8c1<>5
  4. W-Wing: 3/6 in r2c2,r5c1 connected by 6 in r8c12 => r2c1,r4c2<>3
  5. XY-Wing: 2/6/3 in r5c1,r69c3 => r4c3,r7c1<>3
  6. Uniqueness Test 4: 2/9 in r7c58,r8c58 => r78c8<>2
  7. Sue de Coq: r7c123 - {12357} (r7c6 - {17}, r9c3 - {23}) => r8c12,r9c2<>2, r9c2<>3, r7c7<>1
  8. Empty Rectangle: 2 in b6 (r9c38) => r4c3<>2
  9. Row 4 / Column 3 → 7 (Naked Single)
  10. Row 1 / Column 2 → 7 (Hidden Single)
  11. Locked Candidates Type 1 (Pointing): 8 in b1 => r3c79<>8
  12. AIC: 2/9 9- r7c5 =9= r7c8 =8= r7c7 -8- r1c7 =8= r1c9 -8- r6c9 -1- r4c7 =1= r8c7 =2= r8c5 -2 => r7c5<>2, r8c5<>9
  13. Row 7 / Column 5 → 9 (Naked Single)
  14. Row 8 / Column 5 → 2 (Full House)
  15. Row 8 / Column 8 → 9 (Hidden Single)
  16. AIC: 6 6- r6c3 -2- r9c3 =2= r9c8 -2- r7c7 =2= r4c7 =1= r8c7 -1- r8c6 -7- r8c1 -6 => r56c1<>6
  17. Row 5 / Column 1 → 3 (Naked Single)
  18. Row 6 / Column 3 → 6 (Hidden Single)
  19. Naked Pair: 5,6 in r35c7 => r28c7<>5, r2c7<>6
  20. Row 8 / Column 9 → 5 (Hidden Single)
  21. Row 3 / Column 9 → 9 (Naked Single)
  22. Row 1 / Column 3 → 9 (Hidden Single)
  23. Row 2 / Column 2 → 3 (Hidden Single)
  24. Row 2 / Column 7 → 4 (Naked Single)
  25. Row 8 / Column 7 → 1 (Naked Single)
  26. Row 8 / Column 6 → 7 (Naked Single)
  27. Row 7 / Column 6 → 1 (Full House)
  28. Row 8 / Column 1 → 6 (Naked Single)
  29. Row 8 / Column 2 → 4 (Full House)
  30. Row 7 / Column 2 → 2 (Naked Single)
  31. Row 2 / Column 1 → 5 (Naked Single)
  32. Row 2 / Column 8 → 6 (Full House)
  33. Row 9 / Column 2 → 1 (Naked Single)
  34. Row 4 / Column 2 → 8 (Naked Single)
  35. Row 3 / Column 2 → 6 (Full House)
  36. Row 9 / Column 3 → 3 (Naked Single)
  37. Row 3 / Column 3 → 2 (Naked Single)
  38. Row 7 / Column 3 → 5 (Full House)
  39. Row 7 / Column 1 → 7 (Full House)
  40. Row 3 / Column 1 → 8 (Full House)
  41. Row 3 / Column 7 → 5 (Full House)
  42. Row 5 / Column 8 → 5 (Naked Single)
  43. Row 5 / Column 7 → 6 (Full House)
  44. Row 9 / Column 9 → 4 (Naked Single)
  45. Row 9 / Column 8 → 2 (Full House)
  46. Row 6 / Column 8 → 8 (Naked Single)
  47. Row 6 / Column 9 → 1 (Naked Single)
  48. Row 6 / Column 1 → 2 (Full House)
  49. Row 4 / Column 1 → 1 (Full House)
  50. Row 7 / Column 8 → 3 (Naked Single)
  51. Row 4 / Column 8 → 4 (Full House)
  52. Row 7 / Column 7 → 8 (Full House)
  53. Row 4 / Column 9 → 3 (Naked Single)
  54. Row 1 / Column 9 → 8 (Full House)
  55. Row 1 / Column 7 → 3 (Full House)
  56. Row 4 / Column 7 → 2 (Full House)
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