GridMew1Check region A
region A 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 7 other cells.A singleton starts the board, a row scan carries it
Original puzzle gm-5-0034
By GridMew · Published 15 October 2026 · Updated 16 October 2026
5 × 5 practice
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.
Region A forces the top-left cat. The existing cat at r5c4 is far enough away not to touch it. Keep the full row, column and region checks separate from that adjacency observation.
5×5 · 1 fixed cats · 4 explained deductions. Region sizes: A: 1 · B: 8 · C: 6 · D: 6 · E: 4.
A deduction worth checking
Row 4 then resolves at r4c2. Its neighborhood removes r3c3, allowing row 3 to use its rightmost remaining cell.
A move to double-check · r3c3
r3c3 lies in C, not the newly filled D, but still touches r4c2. A region-only update would miss why this candidate disappears.
Green marks the cell being discussed, not a cat to place. This is the position before step 2; 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.
A B B B B B B B B C D D C C C D D C E C D D E E E
Fixed cats: row 5, column 4. One cat is required in each row, column and region.
Step-by-step walkthrough
2Check row 4
row 4 has only one remaining candidate: row 4, column 2. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 2. Place one cat, then exclude 2 other cells.3Check row 3
row 3 has only one remaining candidate: row 3, column 5. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 3. Place one cat, then exclude 1 other cells.4Check row 2
row 2 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 4. 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, r3c5, r4c2, r5c4.
Try another puzzle
Clear the bottom row, then work upward
gm-5-0029 · 5×5 · practice
Practice single-candidate placements on another 5×5 board.
Read this walkthrough →A bottom-left singleton opens a distant column
gm-6-0009 · 6×6 · practice
Transfer single-candidate placements to a 6×6 grid; compare how the candidates change.
Read this walkthrough →Two possible cats, one shared exclusion
gm-5-0001 · 5×5 · challenge
Compare this route with shared-neighbor exclusions, and check why that different rule is needed.
Read this walkthrough →