notes.txt

iterative should be objectively better than recursion

searching by empty space optimizes for dense board layouts
searching by blocks optimizes for sparse layouts

storing as blocks optimizes for search by block
storing as a 2D board optimizes for empty space search

breadth first looks as many possible ways the blocks can move to in the next step
depth first goes as far as it can on one (random) hunch until it reaches a dead end

USING:
depth first
storing blocks

I think my hashcode has too many collisions