Freecell Solver's To-do list
============================
Shlomi Fish <shlomif@cpan.org>
:Date: 2009-08-14
:Revision: $Id$

Pressing
--------

* Investigate why the Win32 package does not run on Windows XP.
** It runs fine on Windows 7.
** Thanks to Manish Jain for the report.

Non-pressing
------------

* Experiment with +__int128+ in GCC wrt the delta_states (instead of GMP).
See: https://www.nu42.com/2016/01/excellent-optimization-story.html .

* Find how well the solver performs with different permutations of the
order of columns/freecells.
** See if it's possible to combine several scans on such different
permutations.

* Write a "simulator" for new flare-based runs to see how they improve on
the existing runs. It will process the scans' command line based on their
end results and performance and will generate the new estimated performance.

* Write the split-dbm-solver which stores the results on the disk for every
non-reversible-moves offset, and fully-connected-components.

* Make sure the depth_dbm_fc_solver is working on 32-bit architectures.

* See if GCC_INLINE-ing the functions inside fcs_hash.c will yield
any benefit.

* Refer to +expand-solitaire-multi-card-moves+ from the fc-solve process.

* Create a displayer for fc-solve's solutions which will allow seeing where a
card was moved from (using a colored →) and where it was placed.
** Create a GUI version.

* If +-opt+ is specified for the flare, then make sure that if the flares
loop stop it when it's doing the optimization scan, then the optimization scan
goes on until it ends.
** Not sure about it.

* Investigate a way to have positions_by_rank also index according to the
suit, and to traverse only the possible parents or children based on the
suit.

* Investigate ways to perform more pointer arithmetics and
(ptr < end_ptr) ; ptr++ . A lot of code is under-optimized this way.

* In the states handling, there's still some room for pointer arithmetics.

* Implement more of Kevin Atkinson's Common Lisp solver's atomic move types,
and try to construct good heuristics out of them.

* Play with writing a memory-re-cycling Soft-DFS scan: if a sub-tree was
marked as a dead-end, then its states might be able to be placed on a linked
list of states that can be reused.

* PySolFC Deal No. 48007594292403677907 :

--------------------------------------------------------
shlomif:~$ make_pysol_freecell_board.py -t -F 48007594292403677907 | fc-solve -l cpb -sam | grep ^Move | wc -l
106
shlomif:~$ make_pysol_freecell_board.py -t -F 48007594292403677907 | fc-solve --method a-star -to 01234675 -asw 300,1500,0,2,50000 -sam | grep ^Move | wc -l
105
shlomif:~$ make_pysol_freecell_board.py -t -F 48007594292403677907 | fc-solve --method a-star -to 01234675 -asw 40,2,40,0,40 -sam | grep ^Move | wc -l
121
shlomif:~$ make_pysol_freecell_board.py -t -F 48007594292403677907 | fc-solve --method a-star -to 0123467589 -asw 300,1500,0,2,50000 -sam | grep ^Move | wc -l
100
shlomif:~$ make_pysol_freecell_board.py -t -F 48007594292403677907 | fc-solve --method a-star -to 0123467589 -asw 300,1500,0,2,40000 -sam | grep ^Move | wc -l
106
shlomif:~$ make_pysol_freecell_board.py -t -F 48007594292403677907 | fc-solve --method a-star -to 0123467589 -asw 300,1500,0,2,60000 -sam | grep ^Move | wc -l
91
--------------------------------------------------------

--------------------------------------------------------
shlomif:~$ make_pysol_freecell_board.py -F -t 91151234961275807905 | ~/apps/test/fcs/bin/fc-solve  -p -t -sam --method a-star -to 0123467589 -asw 300,1000,0,2,90000 | grep ^Move | wc -l
84
--------------------------------------------------------

However this scan generates takes too much time for most boards (over 100K
iterations).

* PySolFC deal No. 03620802041832966472:

--------------------------------------------------------
shlomif[fcs]:$trunk/fc-solve/source$ make_pysol_freecell_board.py -t -F 03620802041832966472  | ./scripts/summarize-fc-solve -- --method a-star -to 0123467589 -asw 300,1500,99,2,65000
Verdict: Solved ; Iters: 156 ; Length: 87
--------------------------------------------------------


** I solved it at length 87.

* PySolFC deal No. 54369539487824719321:

--------------------------------------------------------
shlomif[fcs]:$trunk/fc-solve/source$ make_pysol_freecell_board.py -F -t 54369539487824719321 | ./scripts/summarize-fc-solve --method a-star -to 0123456789 -asw 3000,100,60,0,500
Verdict: Solved ; Iters: 1325 ; Length: 115
--------------------------------------------------------

** Shlomi Fish solved it in under 110 moves.

* PySolFC deal 96166640969002647853:

--------------------------------------------------------
shlomif[fcs]:$trunk/fc-solve/source$ make_pysol_freecell_board.py -F -t 96166640969002647853 | ./scripts/summarize-fc-solve --method a-star -to 0123467589 -asw 370,0,0,2,90000
Verdict: Solved ; Iters: 615 ; Length: 77
--------------------------------------------------------

** Shlomi Fish solved it in 77 moves.

* PySolFC deal 26892246862786948900:

--------------------------------------------------------
shlomif[fcs]:$trunk/fc-solve/source$ make_pysol_freecell_board.py -F -t 26892246862786948900 | perl scripts/summarize-fc-solve -l qsi --flares-choice fc_solve
Verdict: Solved ; Iters: 195331 ; Length: 98
shlomif[fcs]:$trunk/fc-solve/source$ make_pysol_freecell_board.py -F -t 26892246862786948900 | perl scripts/summarize-fc-solve --method a-star -asw '1,0,4,0,4'   --flares-choice fc_solve
Verdict: Solved ; Iters: 111 ; Length: 92
--------------------------------------------------------

** Shlomi Fish solved it in 92 moves.

* Add the new Freecell Solver-compatible game variants of PySolFC.

* Convert magic rank constants such as 1 or 13 to FCS_MAX_RANK and
FCS_RANK_ACE/etc.

* Investigate:

--------------------------------------------------------
$ make_pysol_freecell_board.py -F -t 00682189035907813607 | perl ../scripts/summarize-fc-solve -l qsi
Verdict: Solved ; Iters: 157905 ; Length: 109
$ make_pysol_freecell_board.py -F -t 00682189035907813607 | perl ../scripts/summarize-fc-solve --method a-star -to '01234567' -asw 1 -opt
Verdict: Solved ; Iters: 433 ; Length: 89
--------------------------------------------------------

Long-term
---------

* Integrate the patsolve's prioritization and mixed BFS/DFS scan.

* Update the architecture document.

* Make a super-strict parsable-output without all the quirks of
-p -t (see Games-Solitaire-Verify for why).
** Perhaps see: http://tech.groups.yahoo.com/group/fc-solve-discuss/message/1264 .

* Write a multi-threaded version.

* Port to Java (?)

* Add a switch to ask the user if he wants to continue and enter a bigger
iterations limit.

* Check for unmalloced data and if so gracefully exit.

* Experiment with a delta-based state storage.
    - see delta_states_debondt.c - port it to the main libfreecell-solver.
    - see: http://fc-solve.shlomifish.org/to-do.html#orig_calc_states .

* Make the dbm_fc_solver not dependent on http://gmplib.org/ by implementing
our own big ints.

* Adapt the scans based on the parameters of the initial board.
+
** Try to find a correlation between various parameters of the initial board
(such as those calculated in the A* scan or the number of steps required to
sort the cards in each column by rank), and the performance of various scans
and then:
+
1. Calculate the initial parameters on startup.
+
2. See what would be a good meta-scan based on them.
+
3. Use it.

* Unit-test +fc_solve_compare_lru_cache_keys+ in +scans.c+.

* Interactive mode? Continue a scan that reached its limit.

To be considered
----------------

* Make the code https://sourceforge.net/projects/splint/[splint]-clean.

* Write a multi-process client/server program.

* Add a limit to stacks number (in the case of Indirect Stack States),
number of states that are stored anywhere, etc.

