Mahjong seating generator in Mercury

What does this program compute?

Tournament grids (player seatings) for the Riichi Mahjong game. Players are represented simply by integers: 1, 2, 3, 4, and so on. The generated results comprise a full tournament schedule, listing tables of every hanchan. Each table lists 4 players. Solutions contain no "intersections": not a single pair of players meet more than once during the whole tournament.

Once compiled, usage is as simple as:

./mjseating -P <NUM_PLAYERS> -H <NUM_HANCHANS>

Be aware that the search will likely take a long time. 24-player-6-hanchan computation been running for 23 to 29 hours on my machine to find any results. Smaller parameters of course will run faster. 20-player-5-hanchan solves in <1s.

You'll find samples of generated seatings under data/. There's also a little python helper script to re-check solution correctness (0 intersections).

Please let me know if you find this useful.

Building

Use mmc (the Melbourne Mercury Compiler):

mmc --grade hlc.gc -O2 mjseating

Tracing (debug logs)

env TRACE=1 ./mjseating -P16 -H4

Debugging with mdb

mmc --grade reg.gc.decldebug.stseg mjseating.m
mdb ./mjseating -P16 -H4

Debugging user guide: https://mercurylang.org/information/doc-release/mercury_user_guide/Debugging.html

Profiling

Recompile in a profiling grade:

mmc --grade reg.gc.profdeep -O2 mjseating.m

Then run. Deep.data is written.

To view the profile, Mercury provides mdprof... which is a CGI script.

With nginx:

        location /cgi-bin/mdprof {
            # spawn-fcgi -u ulidtko -M777 -s /tmp/mdprof-fcgi.sock -- /usr/bin/fcgiwrap -f
            include /etc/nginx/fastcgi_params;
            fastcgi_read_timeout 5s; # default 60s
            fastcgi_param SCRIPT_FILENAME /usr/bin/mdprof_cgi;
            fastcgi_pass unix:/tmp/mdprof-fcgi.sock;
        }

and pass full path to Deep.data in the URL, e.g: http://localhost/cgi-bin/mdprof?/home/ulidtko/code/mjseating/Deep.data

TODO