• Accidental implementation (Expected was heuristic approach)
• Simple logic/no big deal.

How it works:

1. Given an array(1-D) as initial state (Must be of len=16).
2. Check whether goal state is reachable.
3. Find the position of empty None block.
4. Enlist possible moves.
5. Find the cost of each move.
6. Apply move with the minimum cost.
7. Repeat 4,5,6 until goal state is found.

• Algorithm moves on the basis of current possible moves (no track/record).
• Moves with no/same minimum cost ends to repetition.
• Repetition is somehow solved using randomness but complicates the problem.