Project Euler > Problem 189 > Tri-colouring a triangular grid (Java Solution)

Problem:

Consider the following configuration of 64 triangles:

We wish to colour the interior of each triangle with one of three colours: red, green or blue, so that no two neighbouring triangles have the same colour. Such a colouring shall be called valid. Here, two triangles are said to be neighbouring if they share an edge.
Note: if they only share a vertex, then they are not neighbours.

For example, here is a valid colouring of the above grid:

A colouring C' which is obtained from a colouring C by rotation or reflection is considered distinct from C unless the two are identical.

How many distinct valid colourings are there for the above configuration?

Solution:

840

Code:
The solution may include methods that will be found here: Library.java .

public interface EulerSolution{

public String run();

}

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