Meowdoku!: How to Cross Out the Middle of a Five-Cell U

When you encounter a five-cell, U-shaped territory in Meowdoku!, immediately place an X on the open middle notch sitting between the two arms. You do not need to determine where the cat actually sits within the U first. Because Meowdoku! forbids cats from touching one another orthogonally or diagonally, every single space in that five-cell formation directly blocks the middle notch.

The Adjacency Logic Behind the 5-Cell U

A five-cell U pattern spans a 3x2 grid area where five colored cells surround a single indented square on three sides. Each colored region in Meowdoku! must contain exactly one cat. Furthermore, cats cannot touch across edges or corners.

Because the central notch borders every single cell of the 3x2 boundary, placing a cat anywhere inside that five-cell group inevitably touches and invalidates the center square:

Even if some squares inside the U are already eliminated by other lines, any remaining candidate square still reaches the notch. Since the region's cat must land in one of those cells, the middle notch can never hold a cat.

How to Execute the Deduction

Follow these steps when scanning a board to eliminate cells without burning your mistake counter:

1. Spot the U-Shape: Locate a five-cell territory wrapping around a single foreign cell on three sides.
2. Confirm the Boundaries: Ensure the notch touches both upright tips horizontally and the base vertically or diagonally.
3. Mark the Center X: Place an X directly onto the middle notch square before trying to resolve the U region itself.
4. Scan Intersecting Lines: Check the row, column, and territory that own the newly marked square.

Crossing out this single cell reduces the remaining options in its row and column. If that line had only two available squares left, eliminating the middle notch immediately forces the cat into the remaining open tile elsewhere on the grid.