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

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): 1 in b9 => r2c7<>1
  2. Skyscraper: 7 in r1c6,r4c4 (connected by r14c7) => r23c4,r5c6<>7
  3. Skyscraper: 8 in r2c7,r3c5 (connected by r8c57) => r2c4,r3c89<>8
  4. W-Wing: 2/4 in r6c4,r9c6 connected by 4 in r2c46 => r5c6,r9c4<>2
  5. XY-Wing: 4/5/2 in r14c5,r6c4 => r3c4,r5c5<>2
  6. Uniqueness Test 4: 1/5 in r2c38,r3c38 => r23c8<>5
  7. Sue de Coq: r3c456 - {23578} (r3c1 - {37}, r1c5 - {25}) => r1c6<>2, r12c6,r2c4<>5, r3c9<>7
  8. Empty Rectangle: 5 in b6 (r1c58) => r5c5<>5
  9. Row 5 / Column 5 → 3 (Naked Single)
  10. Row 7 / Column 6 → 3 (Hidden Single)
  11. Locked Candidates Type 1 (Pointing): 6 in b8 => r8c79<>6
  12. Discontinuous Nice Loop: 8/9 r2c8 =1= r2c3 =5= r2c9 =7= r5c9 -7- r4c7 -6- r7c7 =6= r7c9 -6- r3c9 =6= r3c8 =1= r2c8 => r2c8<>8, r2c8<>9
  13. Row 2 / Column 8 → 1 (Naked Single)
  14. Row 2 / Column 3 → 5 (Naked Single)
  15. Row 3 / Column 3 → 1 (Full House)
  16. AIC: 4 4- r2c4 -3- r2c1 -7- r2c9 =7= r5c9 =5= r3c9 -5- r1c8 =5= r1c5 -5- r4c5 -4 => r46c4<>4
  17. Row 6 / Column 4 → 2 (Naked Single)
  18. Row 4 / Column 5 → 4 (Hidden Single)
  19. Naked Pair: 4,8 in r68c9 => r29c9<>8, r9c9<>4
  20. Row 2 / Column 7 → 8 (Hidden Single)
  21. Row 8 / Column 7 → 1 (Naked Single)
  22. Row 7 / Column 5 → 1 (Hidden Single)
  23. Row 9 / Column 6 → 2 (Hidden Single)
  24. Row 9 / Column 9 → 9 (Naked Single)
  25. Row 2 / Column 9 → 7 (Naked Single)
  26. Row 2 / Column 1 → 3 (Naked Single)
  27. Row 3 / Column 1 → 7 (Full House)
  28. Row 2 / Column 4 → 4 (Naked Single)
  29. Row 2 / Column 6 → 9 (Full House)
  30. Row 3 / Column 6 → 5 (Naked Single)
  31. Row 9 / Column 4 → 8 (Naked Single)
  32. Row 9 / Column 8 → 4 (Full House)
  33. Row 1 / Column 6 → 7 (Naked Single)
  34. Row 1 / Column 5 → 2 (Naked Single)
  35. Row 5 / Column 6 → 6 (Naked Single)
  36. Row 8 / Column 6 → 4 (Full House)
  37. Row 3 / Column 4 → 3 (Naked Single)
  38. Row 3 / Column 5 → 8 (Full House)
  39. Row 8 / Column 5 → 5 (Full House)
  40. Row 8 / Column 4 → 6 (Full House)
  41. Row 8 / Column 9 → 8 (Full House)
  42. Row 6 / Column 8 → 8 (Naked Single)
  43. Row 6 / Column 9 → 4 (Full House)
  44. Row 1 / Column 7 → 9 (Naked Single)
  45. Row 1 / Column 8 → 5 (Full House)
  46. Row 4 / Column 8 → 6 (Naked Single)
  47. Row 3 / Column 8 → 2 (Naked Single)
  48. Row 3 / Column 9 → 6 (Full House)
  49. Row 5 / Column 8 → 9 (Full House)
  50. Row 4 / Column 7 → 7 (Naked Single)
  51. Row 4 / Column 4 → 5 (Full House)
  52. Row 5 / Column 4 → 7 (Full House)
  53. Row 7 / Column 9 → 2 (Naked Single)
  54. Row 5 / Column 9 → 5 (Full House)
  55. Row 5 / Column 7 → 2 (Full House)
  56. Row 7 / Column 7 → 6 (Full House)
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