Cats & Dogs #112: 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 R1C4 and R1C3 means they are the same. R1C4 is a cat, so R1C3 is a cat.
  2. The = clue between R4C1 and R3C1 means they are the same. R4C1 is a cat, so R3C1 is a cat.
  3. The = clue between R7C7 and R8C7 means they are the same. R7C7 is a dog, so R8C7 is a dog.
  4. R1C3 and R1C4 are both cats, so R1C2 must be a dog (no three in a row).
  5. R1C3 and R1C4 are both cats, so R1C5 must be a dog (no three in a row).
  6. R4C1 and R4C3 are both cats with one square between them, so R4C2 must be a dog.
  7. R7C6 and R7C7 are both dogs, so R7C5 must be a cat (no three in a row).
  8. R7C6 and R7C7 are both dogs, so R7C8 must be a cat (no three in a row).
  9. R8C3 and R8C5 are both cats with one square between them, so R8C4 must be a dog.
  10. R3C1 and R4C1 are both cats, so R2C1 must be a dog (no three in a row).
  11. R3C1 and R4C1 are both cats, so R5C1 must be a dog (no three in a row).
  12. R4C3 and R6C3 are both cats with one square between them, so R5C3 must be a dog.
  13. R5C1 and R5C3 are both dogs with one square between them, so R5C2 must be a cat.
  14. R6C3 and R8C3 are both cats with one square between them, so R7C3 must be a dog.
  15. R7C2 and R7C3 are both dogs, so R7C1 must be a cat (no three in a row).
  16. The × clue between R7C1 and R6C1 means they are different. R7C1 is a cat, so R6C1 is a dog.
  17. R7C2 and R7C3 are both dogs, so R7C4 must be a cat (no three in a row).
  18. R5C4 and R7C4 are both cats with one square between them, so R6C4 must be a dog.
  19. R7C5 and R8C5 are both cats, so R6C5 must be a dog (no three in a row).
  20. R6C4 and R6C5 are both dogs, so R6C6 must be a cat (no three in a row).
  21. R7C7 and R8C7 are both dogs, so R6C7 must be a cat (no three in a row).
  22. R6C6 and R6C7 are both cats, so R6C8 must be a dog (no three in a row).
  23. R4C7 and R6C7 are both cats with one square between them, so R5C7 must be a dog.
  24. Row 6 already has its 4 dogs, so R6C2 must be cats.
  25. Column 3 already has its 4 cats, so R2C3 must be dogs.
  26. The × clue between R2C3 and R2C4 means they are different. R2C3 is a dog, so R2C4 is a cat.
  27. R2C1 and R2C3 are both dogs with one square between them, so R2C2 must be a cat.
  28. R1C4 and R2C4 are both cats, so R3C4 must be a dog (no three in a row).
  29. Column 3 already has its 4 cats, so R3C3 must be dogs.
  30. R3C3 and R3C4 are both dogs, so R3C2 must be a cat (no three in a row).
  31. R3C3 and R3C4 are both dogs, so R3C5 must be a cat (no three in a row).
  32. The × clue between R3C5 and R4C5 means they are different. R3C5 is a cat, so R4C5 is a dog.
  33. R4C5 and R6C5 are both dogs with one square between them, so R5C5 must be a cat.
  34. R5C4 and R5C5 are both cats, so R5C6 must be a dog (no three in a row).
  35. R5C6 and R5C7 are both dogs, so R5C8 must be a cat (no three in a row).
  36. Column 2 already has its 4 cats, so R8C2 must be dogs.
  37. The × clue between R8C2 and R8C1 means they are different. R8C2 is a dog, so R8C1 is a cat.
  38. Column 1 already has its 4 cats, so R1C1 must be dogs.
  39. Row 1 already has its 4 dogs, so R1C6 and R1C7 must be cats.
  40. The × clue between R1C7 and R2C7 means they are different. R1C7 is a cat, so R2C7 is a dog.
  41. Column 4 already has its 4 cats, so R4C4 must be dogs.
  42. R4C4 and R4C5 are both dogs, so R4C6 must be a cat (no three in a row).
  43. R4C6 and R4C7 are both cats, so R4C8 must be a dog (no three in a row).
  44. Column 5 already has its 4 cats, so R2C5 must be dogs.
  45. R2C5 and R2C7 are both dogs with one square between them, so R2C6 must be a cat.
  46. R1C6 and R2C6 are both cats, so R3C6 must be a dog (no three in a row).
  47. Row 2 already has its 4 dogs, so R2C8 must be cats.
  48. Column 6 already has its 4 cats, so R8C6 must be dogs.
  49. R8C6 and R8C7 are both dogs, so R8C8 must be a cat (no three in a row).
  50. Column 7 already has its 4 dogs, so R3C7 must be cats.
  51. Row 3 already has its 4 cats, so R3C8 must be dogs.

About this puzzle

This 8×8 grid starts with 12 filled squares and 8 = / × clues. It can be solved in 51 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.

When every square is filled, press Check Answer. The grid is verified against the stored solution and any broken rule is named.

More medium puzzles