Rename hint.txt and hint.text to README.md

2006/night/README.md

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+# Best Abuse of Computation
+
+Christopher Night
+Harvard University
+Department of Astronomy
+Cambrige MA 02238
+US
+<http://www.people.fas.harvard.edu/~night/>
+
+## Judges' Comments:
+
+### To build:
+
+        make night
+
+### To run:
+
+        ./night
+
+You'd never guess, from looking at the code, that there is a
+genetic algorithm involved.  Somewhere.  But what does it do?
+Well, it might take you a while to navigate the results, let
+alone the code.
+
+## Selected Author's Comments:
+
+Don't worry; this is not a self-reproducing program, as you might at
+first guess from the layout. I would never be so foolhardy as to
+submit an entry on an over-used theme!
+
+Oh, wait a second... it is a maze-generating program. Oops!
+
+### What it does:
+
+This program solves an optimization problem, namely, generating a
+challenging maze. It uses a very simple genetic algorithm: a maze
+layout's DNA is represented as a 32-bit integer, and mutations consist
+of flipping three different bits. The algorithm is simple in that it
+doesn't employ sexual reproduction, only mutations, and it has a
+population size of 1. So much for diversity!
+
+This particular optimization problem, I believe, has a unique maximum:
+there is but one maze out of 2^32 that requires 64 moves to solve. The
+program will run until finding this global maximum, or if you get
+bored, you can accept a sub-optimal solution by pressing any key. On
+my system, it takes an average of 15 minutes to find the maximum,
+whereas a random search would take an average of 3.5 days.
+
+Should you take my word for it that the maze it generates requires as
+many moves as I say it does? The answer is yes. But if you're not
+convinced, you can try to solve it yourself. The goal is to traverse
+from the upper-left to the upper-right and out the top, where the
+number of moves remaining is printed. Use the arrow keys for suckers
+(w, a, s, d) to move around. q quits and r restarts. Also, the maze
+changes as you move through it, in a predicatable way. It should be
+easy enough to figure out the pattern. For best results, use a display
+with bold-text capabilities and color.
+
+Finally, in the world of DNA, the medium is truly the message. There's
+a short message encoded in here that will only appear when you
+complete the optimal maze in the required 64 moves.
+
+### Issues:
+
+These depend on your compiler, and they were all intentionally
+added for obfuscation purposes. No, really!
+
+My compiler warns of nulls in a string literal, and the redefinition
+of the macro T.
+
+On one compiler, compilation took about two minutes.
+
+`sizeof(unsigned short)` must be 2, and `sizeof(unsigned long)` must be 4.
+
+CLOCKS_PER_SEC is assumed to be 1000000. If it's a lot less than that,
+expect delays.
+
+### Algorithmic obfuscation:
+
+The representation of the maze layout in a 32-bit integer type is
+pretty opaque. As a hint, the optimum layout's DNA is, in base 4,
+2102231031201230. Try getting from there to the maze that appears on
+screen.
+
+The recursive function CGAC replaces a nested for loop in a handy way.
+
+The maze-solving function TGA returns no solution both if no solution
+exists, and if the search space grows too large, with a single test.
+
+### Stylistic obfuscation:
+
+Four-letter alphabets are confusing. I don't know how ribosomes
+manage.
+
+Overloaded symbols, such as G and G().
+
+Who needs != when you've got ^?
+
+Who needs if when you've got while?
+
+For that matter, who needs fixed-iteration-count for and while when
+you can just duplicate code with the preprocessor? Duplication by this
+macro causes one particular graphics line to be replicated 512
+times. On my system the preprocessed code is over 80KB in length,
+hindering the preprocessor's ability to deobfuscate.
+
+Keypad support was removed to save space. To restore, modify the
+following two macros to:
+
+        #define ATG srand(time(0)); initscr(); cbreak(); noecho(); start_color(); keypad(stdscr,1);
+        #define AGG A&2?KEY_UP:KEY_DOWN:A&1?KEY_RIGHT:KEY_LEFT
+
+Code on!