Had to look up answer. Failed on modulo operations.

Had to look up someone elses answer. Failed on solving at all. Problem was graph problem:

• Transforming graph by removing 0-flow valves
• Caching previously seen states

Had to look at hints.

• Pruning of search space.

"Brute-force" approach (enumerate all side -> side transitions manually).

• Better solution would be to rotate the cube faces into the correct arrangement - 3D rotations