Submitted solution to the ECM competition: https://www.ecmselection.co.uk/articles/ecm-brainbuster-42-office-move Our solution gave the correct answer.

We noted that there are only 6 possible moves possible. From the initial position, we can make the moves: ACD (called CL meaning clockwise left) D (called UD meaning up-down) BED (called AR meaning anticlockwise right). The only other position (which is the exact same as the initial position, but with D in the empty room), we can make the moves: CAD (called AL meaning anticlockwise left) D (called UD meaning up-down) EBD (called CR meaning clockwise right). We keep this notation throughout the programming, and call these the available moves.

The programme works by trialling every possible move available below a known bound which produces a non-optimal solution.