yaworsw/euler-manager

---
:id: 189
:name: Tri-colouring a triangular grid
:url: https://projecteuler.net/problem=189
:content: "Consider the following configuration of 64 triangles:\n\n ![]({{ images_dir
  }}/p189_grid.gif)\n\nWe 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.  \nNote: if they only share a vertex,
  then they are not neighbours.\n\nFor example, here is a valid colouring of the above
  grid:\n\n ![]({{ images_dir }}/p189_colours.gif)\n\nA colouring C' which is obtained
  from a colouring C by rotation or reflection is considered _distinct_ from C unless
  the two are identical.\n\nHow many distinct valid colourings are there for the above
  configuration?\n\n"