Cats & Dogs #144: 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

Use pure logic to place every cat and dog. Each row and column holds 4 of each animal, three in a row is never allowed, and the clues between squares settle the rest.

  • 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 R4C8 and R3C8 means they are different. R4C8 is a cat, so R3C8 is a dog.
  2. The = clue between R3C8 and R3C7 means they are the same. R3C8 is a dog, so R3C7 is a dog.
  3. The = clue between R6C6 and R6C5 means they are the same. R6C6 is a cat, so R6C5 is a cat.
  4. R3C7 and R3C8 are both dogs, so R3C6 must be a cat (no three in a row).
  5. R6C5 and R6C6 are both cats, so R6C4 must be a dog (no three in a row).
  6. R6C2 and R6C4 are both dogs with one square between them, so R6C3 must be a cat.
  7. R6C5 and R6C6 are both cats, so R6C7 must be a dog (no three in a row).
  8. The = clue between R6C7 and R7C7 means they are the same. R6C7 is a dog, so R7C7 is a dog.
  9. The = clue between R7C7 and R7C8 means they are the same. R7C7 is a dog, so R7C8 is a dog.
  10. R7C7 and R7C8 are both dogs, so R7C6 must be a cat (no three in a row).
  11. R8C2 and R8C3 are both dogs, so R8C1 must be a cat (no three in a row).
  12. R8C2 and R8C3 are both dogs, so R8C4 must be a cat (no three in a row).
  13. R6C2 and R8C2 are both dogs with one square between them, so R7C2 must be a cat.
  14. R5C4 and R6C4 are both dogs, so R4C4 must be a cat (no three in a row).
  15. R5C4 and R6C4 are both dogs, so R7C4 must be a cat (no three in a row).
  16. R7C2 and R7C4 are both cats with one square between them, so R7C3 must be a dog.
  17. R7C4 and R7C6 are both cats with one square between them, so R7C5 must be a dog.
  18. R6C6 and R7C6 are both cats, so R5C6 must be a dog (no three in a row).
  19. R5C4 and R5C6 are both dogs with one square between them, so R5C5 must be a cat.
  20. R5C5 and R6C5 are both cats, so R4C5 must be a dog (no three in a row).
  21. R6C6 and R7C6 are both cats, so R8C6 must be a dog (no three in a row).
  22. R6C7 and R7C7 are both dogs, so R5C7 must be a cat (no three in a row).
  23. R6C7 and R7C7 are both dogs, so R8C7 must be a cat (no three in a row).
  24. Row 7 already has its 4 dogs, so R7C1 must be cats.
  25. R7C1 and R8C1 are both cats, so R6C1 must be a dog (no three in a row).
  26. R4C1 and R6C1 are both dogs with one square between them, so R5C1 must be a cat.
  27. Row 6 already has its 4 dogs, so R6C8 must be cats.
  28. R4C8 and R6C8 are both cats with one square between them, so R5C8 must be a dog.
  29. Column 1 already has its 4 cats, so R1C1 must be dogs.
  30. The = clue between R1C1 and R1C2 means they are the same. R1C1 is a dog, so R1C2 is a dog.
  31. R1C1 and R1C2 are both dogs, so R1C3 must be a cat (no three in a row).
  32. R1C3 and R1C4 are both cats, so R1C5 must be a dog (no three in a row).
  33. Column 1 already has its 4 cats, so R2C1 must be dogs.
  34. Column 4 already has its 4 cats, so R2C4 must be dogs.
  35. The = clue between R2C4 and R2C5 means they are the same. R2C4 is a dog, so R2C5 is a dog.
  36. R2C4 and R2C5 are both dogs, so R2C3 must be a cat (no three in a row).
  37. R2C4 and R2C5 are both dogs, so R2C6 must be a cat (no three in a row).
  38. R1C3 and R2C3 are both cats, so R3C3 must be a dog (no three in a row).
  39. R1C5 and R2C5 are both dogs, so R3C5 must be a cat (no three in a row).
  40. R3C5 and R3C6 are both cats, so R3C4 must be a dog (no three in a row).
  41. R3C3 and R3C4 are both dogs, so R3C2 must be a cat (no three in a row).
  42. R2C6 and R3C6 are both cats, so R1C6 must be a dog (no three in a row).
  43. R1C5 and R1C6 are both dogs, so R1C7 must be a cat (no three in a row).
  44. R2C6 and R3C6 are both cats, so R4C6 must be a dog (no three in a row).
  45. R4C5 and R4C6 are both dogs, so R4C7 must be a cat (no three in a row).
  46. Row 1 already has its 4 dogs, so R1C8 must be cats.
  47. Column 5 already has its 4 dogs, so R8C5 must be cats.
  48. Row 8 already has its 4 cats, so R8C8 must be dogs.
  49. Column 7 already has its 4 cats, so R2C7 must be dogs.
  50. Row 2 already has its 4 dogs, so R2C2 must be cats.
  51. R2C2 and R3C2 are both cats, so R4C2 must be a dog (no three in a row).
  52. R4C1 and R4C2 are both dogs, so R4C3 must be a cat (no three in a row).
  53. R4C2 and R6C2 are both dogs with one square between them, so R5C2 must be a cat.
  54. R5C1 and R5C2 are both cats, so R5C3 must be a dog (no three in a row).
  55. Row 2 already has its 4 dogs, so R2C8 must be cats.

About this puzzle

This 8×8 grid starts with 9 filled squares and 7 = / × clues. It can be solved in 55 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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