Cats & Dogs #191: 8x8 Grid Puzzle (Medium)

medium

Tap a square: 🐱 cat → 🐶 dog → clear

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🐱 4 cats and 🐶 4 dogs in every row and column = same   × different

A 8x8 logic grid: 4 cats and 4 dogs in every row and column, no three of a kind in a row, and a few = and × clues to point the way.

  • Exactly 4 cats and 4 dogs in every row and every column.
  • Never three of the same animal in a row, across or down.
  • An = between two squares means the same animal; a × means different animals.

Step-by-step solution

Squares are written as R<row>C<column>, counting from the top-left.

  1. The × clue between R1C4 and R1C3 means they are different. R1C4 is a cat, so R1C3 is a dog.
  2. The × clue between R1C3 and R2C3 means they are different. R1C3 is a dog, so R2C3 is a cat.
  3. The × clue between R7C7 and R7C6 means they are different. R7C7 is a dog, so R7C6 is a cat.
  4. The = clue between R7C6 and R7C5 means they are the same. R7C6 is a cat, so R7C5 is a cat.
  5. The = clue between R7C5 and R8C5 means they are the same. R7C5 is a cat, so R8C5 is a cat.
  6. The = clue between R8C5 and R8C6 means they are the same. R8C5 is a cat, so R8C6 is a cat.
  7. R2C1 and R2C3 are both cats with one square between them, so R2C2 must be a dog.
  8. The = clue between R2C2 and R3C2 means they are the same. R2C2 is a dog, so R3C2 is a dog.
  9. R7C5 and R7C6 are both cats, so R7C4 must be a dog (no three in a row).
  10. R8C5 and R8C6 are both cats, so R8C4 must be a dog (no three in a row).
  11. R8C5 and R8C6 are both cats, so R8C7 must be a dog (no three in a row).
  12. R2C2 and R3C2 are both dogs, so R1C2 must be a cat (no three in a row).
  13. R2C2 and R3C2 are both dogs, so R4C2 must be a cat (no three in a row).
  14. R4C2 and R5C2 are both cats, so R6C2 must be a dog (no three in a row).
  15. R7C4 and R8C4 are both dogs, so R6C4 must be a cat (no three in a row).
  16. R7C5 and R8C5 are both cats, so R6C5 must be a dog (no three in a row).
  17. R7C6 and R8C6 are both cats, so R6C6 must be a dog (no three in a row).
  18. R6C5 and R6C6 are both dogs, so R6C7 must be a cat (no three in a row).
  19. The × clue between R6C7 and R5C7 means they are different. R6C7 is a cat, so R5C7 is a dog.
  20. The × clue between R5C7 and R4C7 means they are different. R5C7 is a dog, so R4C7 is a cat.
  21. R4C7 and R4C8 are both cats, so R4C6 must be a dog (no three in a row).
  22. R4C6 and R6C6 are both dogs with one square between them, so R5C6 must be a cat.
  23. The × clue between R5C6 and R5C5 means they are different. R5C6 is a cat, so R5C5 is a dog.
  24. R5C5 and R6C5 are both dogs, so R4C5 must be a cat (no three in a row).
  25. Row 4 already has its 4 cats, so R4C1, R4C3 and R4C4 must be dogs.
  26. The = clue between R4C4 and R3C4 means they are the same. R4C4 is a dog, so R3C4 is a dog.
  27. The = clue between R3C4 and R3C5 means they are the same. R3C4 is a dog, so R3C5 is a dog.
  28. R3C2 and R3C4 are both dogs with one square between them, so R3C3 must be a cat.
  29. R3C4 and R3C5 are both dogs, so R3C6 must be a cat (no three in a row).
  30. R3C4 and R4C4 are both dogs, so R2C4 must be a cat (no three in a row).
  31. R2C3 and R2C4 are both cats, so R2C5 must be a dog (no three in a row).
  32. R3C4 and R4C4 are both dogs, so R5C4 must be a cat (no three in a row).
  33. R5C2 and R5C4 are both cats with one square between them, so R5C3 must be a dog.
  34. R4C3 and R5C3 are both dogs, so R6C3 must be a cat (no three in a row).
  35. R2C5 and R3C5 are both dogs, so R1C5 must be a cat (no three in a row).
  36. R1C4 and R1C5 are both cats, so R1C6 must be a dog (no three in a row).
  37. Column 6 already has its 4 cats, so R2C6 must be dogs.
  38. R2C5 and R2C6 are both dogs, so R2C7 must be a cat (no three in a row).
  39. R2C7 and R4C7 are both cats with one square between them, so R3C7 must be a dog.
  40. Row 2 already has its 4 cats, so R2C8 must be dogs.
  41. Row 3 already has its 4 dogs, so R3C1 must be cats.
  42. R2C1 and R3C1 are both cats, so R1C1 must be a dog (no three in a row).
  43. Row 3 already has its 4 dogs, so R3C8 must be cats.
  44. R3C8 and R4C8 are both cats, so R5C8 must be a dog (no three in a row).
  45. Row 5 already has its 4 dogs, so R5C1 must be cats.
  46. Column 7 already has its 4 dogs, so R1C7 must be cats.
  47. Row 1 already has its 4 cats, so R1C8 must be dogs.
  48. Column 8 already has its 4 dogs, so R6C8 must be cats.
  49. Row 6 already has its 4 cats, so R6C1 must be dogs.
  50. The = clue between R6C1 and R7C1 means they are the same. R6C1 is a dog, so R7C1 is a dog.
  51. R6C1 and R7C1 are both dogs, so R8C1 must be a cat (no three in a row).
  52. The × clue between R8C1 and R8C2 means they are different. R8C1 is a cat, so R8C2 is a dog.
  53. R8C2 and R8C4 are both dogs with one square between them, so R8C3 must be a cat.
  54. R6C2 and R8C2 are both dogs with one square between them, so R7C2 must be a cat.
  55. R6C3 and R8C3 are both cats with one square between them, so R7C3 must be a dog.
  56. Row 7 already has its 4 dogs, so R7C8 must be cats.

About this puzzle

This 8×8 grid starts with 6 filled squares and 14 = / × clues. It can be solved in 56 steps using pairs, gaps, counts and clues.

Count as you go. Once a row or column has all of one animal, every remaining empty square in it must be the other.

Every puzzle on this site has exactly one solution that can be reached by deduction. If you are guessing, look again at the rows and columns that are nearly full.

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