Cats & Dogs #139: 8x8 Grid Puzzle (Medium)

medium

Tap a square: 🐱 cat → 🐶 dog → clear

0 / 64 · 0:00
🐱 4 cats and 🐶 4 dogs in every row and column = same   × different

Fill the 8x8 grid with cats and dogs so that every row and every column has exactly 4 of each, and never more than two of the same animal side by side.

  • 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 R1C3 and R2C3 means they are different. R1C3 is a cat, so R2C3 is a dog.
  2. The = clue between R2C3 and R2C4 means they are the same. R2C3 is a dog, so R2C4 is a dog.
  3. The = clue between R4C4 and R4C3 means they are the same. R4C4 is a cat, so R4C3 is a cat.
  4. The = clue between R7C5 and R7C6 means they are the same. R7C5 is a cat, so R7C6 is a cat.
  5. The = clue between R7C6 and R6C6 means they are the same. R7C6 is a cat, so R6C6 is a cat.
  6. The × clue between R6C6 and R6C7 means they are different. R6C6 is a cat, so R6C7 is a dog.
  7. The = clue between R6C7 and R6C8 means they are the same. R6C7 is a dog, so R6C8 is a dog.
  8. R2C3 and R2C4 are both dogs, so R2C2 must be a cat (no three in a row).
  9. R2C3 and R2C4 are both dogs, so R2C5 must be a cat (no three in a row).
  10. R4C3 and R4C4 are both cats, so R4C2 must be a dog (no three in a row).
  11. R4C3 and R4C4 are both cats, so R4C5 must be a dog (no three in a row).
  12. R7C3 and R7C5 are both cats with one square between them, so R7C4 must be a dog.
  13. R7C5 and R7C6 are both cats, so R7C7 must be a dog (no three in a row).
  14. R6C6 and R7C6 are both cats, so R5C6 must be a dog (no three in a row).
  15. R5C6 and R5C8 are both dogs with one square between them, so R5C7 must be a cat.
  16. The × clue between R5C7 and R4C7 means they are different. R5C7 is a cat, so R4C7 is a dog.
  17. R4C5 and R4C7 are both dogs with one square between them, so R4C6 must be a cat.
  18. R6C6 and R7C6 are both cats, so R8C6 must be a dog (no three in a row).
  19. The × clue between R8C6 and R8C5 means they are different. R8C6 is a dog, so R8C5 is a cat.
  20. R7C5 and R8C5 are both cats, so R6C5 must be a dog (no three in a row).
  21. R4C5 and R6C5 are both dogs with one square between them, so R5C5 must be a cat.
  22. R3C7 and R4C7 are both dogs, so R2C7 must be a cat (no three in a row).
  23. R2C5 and R2C7 are both cats with one square between them, so R2C6 must be a dog.
  24. R6C7 and R7C7 are both dogs, so R8C7 must be a cat (no three in a row).
  25. The × clue between R8C7 and R8C8 means they are different. R8C7 is a cat, so R8C8 is a dog.
  26. R5C8 and R6C8 are both dogs, so R4C8 must be a cat (no three in a row).
  27. The × clue between R4C8 and R3C8 means they are different. R4C8 is a cat, so R3C8 is a dog.
  28. R3C7 and R3C8 are both dogs, so R3C6 must be a cat (no three in a row).
  29. R5C8 and R6C8 are both dogs, so R7C8 must be a cat (no three in a row).
  30. Row 4 already has its 4 cats, so R4C1 must be dogs.
  31. Row 7 already has its 4 cats, so R7C1 and R7C2 must be dogs.
  32. Column 5 already has its 4 cats, so R1C5 and R3C5 must be dogs.
  33. Column 6 already has its 4 cats, so R1C6 must be dogs.
  34. R1C5 and R1C6 are both dogs, so R1C4 must be a cat (no three in a row).
  35. R1C3 and R1C4 are both cats, so R1C2 must be a dog (no three in a row).
  36. R1C5 and R1C6 are both dogs, so R1C7 must be a cat (no three in a row).
  37. Column 8 already has its 4 dogs, so R1C8 must be cats.
  38. Row 1 already has its 4 cats, so R1C1 must be dogs.
  39. Column 8 already has its 4 dogs, so R2C8 must be cats.
  40. Row 2 already has its 4 cats, so R2C1 must be dogs.
  41. R1C1 and R2C1 are both dogs, so R3C1 must be a cat (no three in a row).
  42. Column 1 already has its 4 dogs, so R5C1 and R6C1 must be cats.
  43. The × clue between R6C1 and R6C2 means they are different. R6C1 is a cat, so R6C2 is a dog.
  44. R4C2 and R6C2 are both dogs with one square between them, so R5C2 must be a cat.
  45. R5C1 and R5C2 are both cats, so R5C3 must be a dog (no three in a row).
  46. R6C2 and R7C2 are both dogs, so R8C2 must be a cat (no three in a row).
  47. Row 5 already has its 4 cats, so R5C4 must be dogs.
  48. R5C4 and R7C4 are both dogs with one square between them, so R6C4 must be a cat.
  49. Row 6 already has its 4 dogs, so R6C3 must be cats.
  50. R6C3 and R7C3 are both cats, so R8C3 must be a dog (no three in a row).
  51. Column 1 already has its 4 dogs, so R8C1 must be cats.
  52. Row 8 already has its 4 cats, so R8C4 must be dogs.
  53. Column 2 already has its 4 dogs, so R3C2 must be cats.
  54. R3C1 and R3C2 are both cats, so R3C3 must be a dog (no three in a row).
  55. R3C3 and R3C5 are both dogs with one square between them, so R3C4 must be a cat.

About this puzzle

This 8×8 grid starts with 6 filled squares and 12 = / × clues. It can be solved in 55 steps using pairs, gaps, counts and clues.

Watch for a gap: if the squares on either side of an empty square match, the empty one must be different.

Stuck? Open the step-by-step solution below -- each step names the squares involved, so you can use it as a hint and finish the puzzle yourself.

More medium puzzles