Puzzle gm-8-0011

8 × 8 intro

Take this puzzle one clear step at a time.

Try the puzzle yourself, then explore how the deductions build.

Puzzle board · starting state

Your starting point

This original 8×8 board has 8 connected regions and 2 fixed cats. The smallest region is A, with 2 cells. Start by ruling out every other cell in each fixed cat’s row, column and region, plus its immediate neighbors.

The verified route below uses 6 forced placements and 0 candidate-elimination steps after the givens. Region sizes: A: 2 · B: 4 · C: 14 · D: 4 · E: 4 · F: 13 · G: 17 · H: 6. These are observations about this board, not a guarantee that a smaller region always contains the next move.

Read each diagram in sequence. Cats and × marks in the before-state come from earlier deductions. Green outlines identify the current observation. Open the final answer only when you want the spoiler.

Step-by-step walkthrough

1Check column 1

column 1 has only one remaining candidate: row 1, column 1. Every other cell is excluded by earlier placements or deductions. Place the cat here.

Before step 1. Place one cat, then exclude 5 other cells.

2Check column 3

column 3 has only one remaining candidate: row 2, column 3. Every other cell is excluded by earlier placements or deductions. Place the cat here.

Before step 2. Place one cat, then exclude 3 other cells.

3Check region E

region E has only one remaining candidate: row 5, column 8. Every other cell is excluded by earlier placements or deductions. Place the cat here.

Before step 3. Place one cat, then exclude 6 other cells.

4Check region C

region C has only one remaining candidate: row 3, column 7. Every other cell is excluded by earlier placements or deductions. Place the cat here.

Before step 4. Place one cat, then exclude 4 other cells.

5Check row 4

row 4 has only one remaining candidate: row 4, column 5. Every other cell is excluded by earlier placements or deductions. Place the cat here.

Before step 5. Place one cat, then exclude 1 other cells.

6Check row 8

row 8 has only one remaining candidate: row 8, column 6. Every other cell is excluded by earlier placements or deductions. Place the cat here.

Before step 6. Place one cat, then exclude 0 other cells.

Show solution · reveals all cat positions

The final cats satisfy every row, column and region quota, with no edge or corner contact.

Cat positions: r1c1, r2c3, r3c7, r4c5, r5c8, r6c4, r7c2, r8c6.