5.4. The BrFS Optimization Scan

• Stephan Kulow (of KDE fame) complained that Freecell Solver generated some extremely long solutions, which just moved sequences from one stack to the the other.
• I suggested to use a Breadth-First Search scan restricted to the states that were found in the solution path to try to eliminate redundant moves.
• This turned out to be quite beneficial in most cases.
• I later on implemented a scheme in which each state stored a pointer to its "parent" state (the state from which it was initially discovered). and used back-tracking to trace the solution down there.
• This turned out to optimize solutions as well, but the BrFS optimization improved it a bit too sometimes.

Written by Shlomi Fish