Medusa Coloring

Level 12 · Black Belt

Strategy:

Coloring

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

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

Example

Starting position

Look for Medusa Coloring.

1

Build the 3D Medusa coloring network

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

2

One color is true, the other false

Exactly one color is true for each digit, and the other color is false.

3

2 at r3c7 sees both colors

Uncolored candidate 2 at r3c7 sees both colored versions of this digit.

4

2 at r3c7 is trapped

One of those must be true, so 2 at r3c7 is the candidate to remove.

5

Remove 2 from r3c7

Eliminate 2 from r3c7.

6

Result

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.