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.

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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