GridMew1Check region A
region A 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 1. Place one cat, then exclude 4 other cells.Reserve the middle of column 4 indirectly
Original puzzle gm-5-0019
By GridMew · Published 15 October 2026 · Updated 16 October 2026
5 × 5 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 given in column 5 reduces region A to its top cell. After that single, inspect column 3 as a group: its three possible cats share a neighbor in column 4.
5×5 · 1 fixed cats · 5 explained deductions. Region sizes: A: 2 · B: 8 · C: 2 · D: 7 · E: 6.
A deduction worth checking
r3c3, r4c3 and r5c3 all touch r4c4. Excluding that shared neighbor creates the column-4 single at r5c4.
A move to double-check · r4c4
There is no need to place a column-3 cat first. Any of its three surviving choices would conflict with a cat at r4c4.
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.
D A B B B D A B B B D D C B B D D C E E D E E E E
Fixed cats: row 2, column 5. One cat is required in each row, column and region.
Step-by-step walkthrough
2Exclude common neighbors
The cat in column 3 must occupy one of row 3, column 3; row 4, column 3; row 5, column 3. Each of row 4, column 4 touches every candidate, so none can hold a cat.
Before step 2. Exclude 1 cells; then scan for a new single.3Check column 4
column 4 has only one remaining candidate: row 5, column 4. 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 4
row 4 has only one remaining candidate: row 4, 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 3
row 3 has only one remaining candidate: row 3, column 3. 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, r2c5, r3c3, r4c1, r5c4.
Try another puzzle
Two possible cats, one shared exclusion
gm-5-0001 · 5×5 · challenge
Practice shared-neighbor exclusions on another 5×5 board.
Read this walkthrough →A shared neighborhood settles the right edge
gm-6-0007 · 6×6 · challenge
Transfer shared-neighbor exclusions to a 6×6 grid; compare how the candidates change.
Read this walkthrough →A bottom-row single reaches a right-edge region
gm-6-0001 · 6×6 · practice
Compare this route with single-candidate placements, and check why that different rule is needed.
Read this walkthrough →