GridMew1Check region B
region B has only one remaining candidate: row 2, 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.Two possible cats, one shared exclusion
Original puzzle gm-5-0001
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 fixed cat at r1c3 leaves region B with just r2c1. Once B is filled, stop looking for another immediate cat: the useful information is the pair of possibilities at the right end of row 3.
5×5 · 1 fixed cats · 5 explained deductions. Region sizes: A: 3 · B: 4 · C: 6 · D: 9 · E: 3.
A deduction worth checking
Row 3 can use r3c4 or r3c5. Both possibilities touch r4c4 and r4c5, so row 4 loses those cells before either row-3 position is chosen.
A move to double-check · r4c4
Do not pick one of the two row-3 candidates to justify crossing out r4c4. The exclusion works because both candidates touch it; choosing either one would add an unnecessary assumption.
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.
B B A A C B B D A C D D D D C D D D C C D E E E C
Fixed cats: row 1, column 3. One cat is required in each row, column and region.
Step-by-step walkthrough
2Exclude common neighbors
The cat in row 3 must occupy one of row 3, column 4; row 3, column 5. Each of row 4, column 4; row 4, column 5 touches every candidate, so none can hold a cat.
Before step 2. Exclude 2 cells; then scan for a new single.3Check 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 3. Place one cat, then exclude 2 other cells.4Check 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 4. Place one cat, then exclude 1 other cells.5Check row 5
row 5 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 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: r1c3, r2c1, r3c5, r4c2, r5c4.
Try another puzzle
Reserve the middle of column 4 indirectly
gm-5-0019 · 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 →