Those subgraphs can then be used to arrange the cubes and solve the puzzle. It s largely a matter of following the edges in the right order along a particular circuit of the subgraph. All this may look somewhat cumbersome, but the graph approach is surely more efficient than trying thousands of combinations with no guarantee of success. Those familiar with graph theory can typically work out the solution in minutes. Indeed, the puzzle serves as a neat lesson in logical thinking.
Puzzles are problems done for fun.
J.H. Conway, and R.K. Guy. Winning Ways for Your Mathematical Plays. Chartrand, G. 1985. Introductory Graph Theory . Deventer, J.V. 1969.