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

2005/timwi/README.md

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+# Most discourteous interpreter
+
+Arne "Timwi" Heizmann
+Germany
+timwi@gmx.net
+
+## Judges' notes
+
+### To build
+
+        cc timwi.c -o timwi
+
+### To run
+
+        timwi < bf_program
+
+Unlike most BF interpreters that we have been receiving for the last few
+years, this one, in our opinion, is the most obfuscated albeit the most
+discourteous to the language it interprets. A simple 3-character fix will make
+it slightly less so.
+
+Quite a few BF programs found on the Net expect byte-based memory, quite a few
+exceed the capacity of this interpreter, but there are many that work. Some
+small quines work, some don't.
+
+Why?
+
+## Selected notes from the author
+
+This is an interpreter for the programming language BrainFuck (BF).
+
+Input must be provided in the following format: First a sequence of integers
+separated by whitespace (this will be the input to the BF program), then a
+colon (:), then the BF program itself.
+
+Example:
+
+        (echo "20 : ,-->+.>+.<<[>[>>+>+<<<-]>[>>+>+<<<-]>";
+
+        echo "[<+>-]>[<<<+>>>-]>[-]<<<<.<-]") | timwi
+
+This will print the first 20 Fibonacci numbers.
+
+You must not pass any command-line arguments.
+
+### Features
+
+  * Supports the complete set of 8 BF instructions (+-<>[].,).
+  * Supports the use of alternative characters for some of those instructions.
+Use this to obfuscate your BF programs!
+
+For a challenge, figure out what this obfuscated BF program does:
+
+        J4mzt?Vazexx-20d~&&~AxdUV!x(~Jz&V)x*(P=J)JUN(dizz)xx_!xx'0&{Vz;}&Jj
+
+It takes two integers as input and outputs one integer.
+
+  * Ignores all whitespace (newlines, spaces and tabs) in the input program.
+
+### Limitations
+
+Since the program, naturally, uses ints, the calculations must not exceed the
+range of an int. (But then again, you can use the integer overflow to further
+obfuscate your BF programs in creative ways!)
+
+You are limited to 3125 input integers and 3125 instructions. If you exceed
+one of these limits, the behaviour is undefined.
+
+### Obfuscations
+
+Some of the superficial obfuscations are pretty obvious: I'm using #defines to
+make everything look nice and liney, and the program is merely a recursive
+main function with only a single 'return' statement which uses nested ternary
+operators to make even the pre-processed code unreadable.
+
+However, the more subtle obfuscations relate to the way the program works.
+After applying the pre-processing, you will see a lot of "1+1+1+...etc.", and
+even if you replace these with their result, those numbers will still not
+represent (or even relate to) the ASCII codes of the BF instructions.
+
+The program will first read in all the input integers, but it will begin
+execution immediately and only read program instructions as they are needed.
+Yet there is no global variable storing how far it has read! Perhaps the
+hardest thing to figure out is how it finds the matching square brackets.