GridMew1Check region B
region B has only one remaining candidate: row 2, column 2. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 1. Place one cat, then exclude 7 other cells.Use two row locks at different stages of the solve
Original puzzle gm-8-0008
By GridMew · Published 15 October 2026 · Updated 16 October 2026
8 × 8 challenge
Read the starting position, follow the deductions, and check the move that is easy to misread.
Puzzle board · starting state
How to approach this board
Coordinates such as r2c3 mean row 2, column 3. Count rows from the top and columns from the left.
The upper given reduces B to r2c2. After this single, row 3’s candidates all lie in C. Its reservation clears row 4, while a later reservation in F handles the lower-right corner.
8×8 · 2 fixed cats · 9 explained deductions. Region sizes: A: 6 · B: 4 · C: 13 · D: 21 · E: 5 · F: 6 · G: 5 · H: 4.
A deduction worth checking
At step 5, row 6 is confined to F at columns 6–8. That removes r7c8; the following shared-neighbor step removes r7c7.
A move to double-check · r7c8
Do not combine these two exclusions into one vague adjacency claim. r7c8 is removed by the F quota; r7c7 is removed by touching every row-6 candidate.
Green marks the cell being discussed, not a cat to place. This is the position before step 5; compare the deduction below.
Read the starting board as text
Each line is one row, left to right. Matching letters belong to the same connected region.
B B D D A A A A B B D C A A C C E D D C C C C C E D D C C C C C E E D D D D F F E D D D D F F F D D D D G G G F D D H H H H G G
Fixed cats: row 1, column 5; row 5, column 1. One cat is required in each row, column and region.
Step-by-step walkthrough
2Use a candidate lock
Every candidate in row 3 lies in region C (row 3, column 4; row 3, column 6; row 3, column 7; row 3, column 8). Its cat must use that shared section. Exclude row 4, column 4; row 4, column 6; row 4, column 7; row 4, column 8 from the rest of region C.
Before step 2. Exclude 4 cells; then scan for a new single.3Check row 4
row 4 has only one remaining candidate: row 4, column 3. 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 column 4
column 4 has only one remaining candidate: row 8, column 4. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 4. Place one cat, then exclude 3 other cells.5Use a candidate lock
Every candidate in row 6 lies in region F (row 6, column 6; row 6, column 7; row 6, column 8). Its cat must use that shared section. Exclude row 7, column 8 from the rest of region F.
Before step 5. Exclude 1 cells; then scan for a new single.6Exclude common neighbors
The cat in row 6 must occupy one of row 6, column 6; row 6, column 7; row 6, column 8. Each of row 7, column 7 touches every candidate, so none can hold a cat.
Before step 6. Exclude 1 cells; then scan for a new single.7Check row 7
row 7 has only one remaining candidate: row 7, column 6. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 7. Place one cat, then exclude 3 other cells.8Check row 6
row 6 has only one remaining candidate: row 6, column 8. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 8. Place one cat, then exclude 1 other cells.9Check row 3
row 3 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 9. 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: r1c5, r2c2, r3c7, r4c3, r5c1, r6c8, r7c6, r8c4.
Try another puzzle
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