GridMew1Check region E
region E has only one remaining candidate: row 5, column 5. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 1. Place one cat, then exclude 9 other cells.A one-cell region starts a column cascade
Original puzzle gm-5-0007
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 E is the single bottom-right cell. It forces a cat without a given. Its effect on column 5 then shrinks region B, letting a tiny region influence the opposite end of the board.
5×5 · 0 fixed cats · 5 explained deductions. Region sizes: A: 7 · B: 3 · C: 3 · D: 11 · E: 1.
A deduction worth checking
With column 5 occupied, B is reduced to r2c4. That cat removes r1c3 and r3c3 by corner contact, preparing the column-3 single.
A move to double-check · r3c3
After placing r2c4, r3c3 cannot stay available just because it lies in the larger region D. The immediate diagonal contact is enough to exclude it.
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 A A A B A A A B B C D D D D C D D D D C D D D E
Fixed cats: none. One cat is required in each row, column and region.
Step-by-step walkthrough
2Check region B
region B has only one remaining candidate: row 2, column 4. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 2. Place one cat, then exclude 7 other cells.3Check column 3
column 3 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 3 other cells.4Check row 3
row 3 has only one remaining candidate: row 3, column 1. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 4. Place one cat, then exclude 1 other cells.5Check row 1
row 1 has only one remaining candidate: row 1, column 2. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Before step 5. 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: r1c2, r2c4, r3c1, r4c3, r5c5.
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.
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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 →