Medusa Coloring

Level 12 · Black Belt

Strategy:

Requires:

Simple Coloring

Overview

Medusa Coloring (3D Medusa) extends Simple Coloring to multiple digits by using strong links within bi-value cells. This builds larger color clusters with more elimination opportunities.

How It Works

Start with conjugate pairs and color alternately as in Simple Coloring.
When reaching a bi-value cell, continue coloring to the other candidate.
Build clusters across multiple digits using this 3D approach.
Apply rules: same color twice in unit/cell = false; uncolored seeing both colors = eliminated.

Example

Look for Medusa Coloring.

Sudoku grid showing the initial puzzle state for Look for Medusa Coloring.

1

Medusa Coloring

Build a 3D Medusa coloring network by alternating colors along strong links.

Sudoku grid illustrating step 1: Medusa Coloring — Build a 3D Medusa coloring network by alternating colors along strong links.

2

Medusa Coloring

Exactly ONE color is TRUE for each digit - the other color is FALSE.

Sudoku grid illustrating step 2: Medusa Coloring — Exactly ONE color is TRUE for each digit - the other color is FALSE.

3

Medusa Coloring

Uncolored candidate 1 at r7c6 sees BOTH colored versions of this digit.

Sudoku grid illustrating step 3: Medusa Coloring — Uncolored candidate 1 at r7c6 sees BOTH colored versions of this digit.

4

Medusa Coloring

One of those must be TRUE, so 1 at r7c6 is the candidate to remove.

Sudoku grid illustrating step 4: Medusa Coloring — One of those must be TRUE, so 1 at r7c6 is the candidate to remove.

5

Medusa Coloring

Eliminate 1 from r7c6.

Sudoku grid illustrating step 5: Medusa Coloring — Eliminate 1 from r7c6.

6

Result after applying the technique.

Sudoku grid showing the result after applying the technique

Tips & Patterns

Medusa expands 2D coloring into a third dimension via bi-value cells.
The same elimination rules apply but across multiple digits.
Clusters can grow much larger than single-digit coloring.