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

2023-02-08 05:08:28 -08:00
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+# Most shifty
+
+Don Yang  
+<http://uguu.org/>  
+
+
+## Judges' comments:
+### To use:
+
+    make
+    more generated1.c
+    more generated2.c
+    more generated3.c
+
+### Try:
+
+    make
+    ./left < prog.c
+    ./right < prog.c
+    ./left < prog.c | ./left
+
+    ./shift < prog.c
+
+    ./msg0
+    ./msg1
+    ./msg2
+
+### Selected Judges Remarks:
+
+Code should be readable in any direction! This tool will help you rotate your
+code so you don't have to stare at it sideways or even upside down. Rotating
+this program left and recompiling will reveal other tools including a right rotate
+and a shift program.
+
+Strange things happen when the world is upside down! It is entirely possible
+that this is remark is completely misleading.
+
+What exactly does the shift program do?
+
+Like a great sliding puzzle (hint) this entry has 6 more programs that will
+reveal messages and one more tool that can be used to reveal the final
+message hidden in the original source.  All of these can be created using
+combinations of ./left, ./right and ./shift and the additionally generated
+programs.
+
+The final message can be revealed using
+
+    ./msg9 < prog.c
+
+But what combinations will generate ./msg3, ./msg4, ./msg5, ./msg6, ./msg7,
+./msg8 and finally ./msg9?
+
+## Author's comments:
+# Tools usage
+
+Nuko is a text rotator: given some text in stdin, Nuko will write the
+same text to stdout, but rotated 90 degrees counterclockwise.
+
+    gcc prog.c -o left
+    ./left < input.txt > rotated_counterclockwise.txt
+
+Due to static memory allocation, only the first 1K columns by 1K rows
+are rotated, the rest are silently ignored.  But fear not, a separate
+tool with dynamic memory allocation is included:
+
+    ./left < prog.c > r1.c
+    gcc r1.c -o right
+    ./right < input.txt > rotated_clockwise.txt
+
+For variety, this second tool rotates clockwise instead of
+counterclockwise.  Also, it can handle files larger than 1024x1024,
+depending on how much memory you got.
+
+Of course we wouldn't stop with just two rotations, if we continue to
+rotate counterclockwise once more, we get another program.  This
+program outputs a single message to stdout, which is the name of the
+series that Nuko came from.
+
+    ./left < prog.c | ./left > r2.c
+    gcc r2.c -o msg0
+    ./msg0
+
+There is one final rotation, which produces a tool that removes
+leading whitespaces:
+
+    ./left < prog.c | ./left | ./left > r3.c
+    gcc r3.c -o shift
+    ./shift < input.txt > no_leading_space.txt
+
+Where this might be useful, besides ruining the formatting of certain
+files, is that it completes the set of tools needed to solve the
+puzzle that is embedded in prog.c
+
+# Puzzle box
+
+Notice how the edges of prog.c contain two notches.  By rotating
+prog.c and removing leading space, the code would be shifted one space
+toward one of those notches (and creating a new notch on the other
+side).  This shifted code behaves slightly different from the original
+program.  For example, here are two more messages that can be
+produced:
+
+    ./shift < prog.c | ./right > msg1.c && gcc msg1.c -o msg1 && ./msg1
+    ./shift < prog.c | ./left > msg2.c && gcc msg2.c -o msg2 && ./msg2
+
+In total, there are 9 embedded strings that can be produced via a
+sequence of rotates and shifts, one of which can be used to extract
+the 10th final string from prog.c.  The intent is to simulate those
+wooden puzzle boxes that can be opened by pushing and shifting various
+well-concealed seams.  Thus, finding the correct sequence of rotates
+and shifts is left as an exercise to the reader (but if you are really
+lazy, just read the Makefile).
+
+Source code for all the tools needed to solve this puzzle are embedded
+in prog.c, all you need is a C compiler.
+
+# Features
+
+   - Code compiles when rotated 4 ways.  This required a bit of
+     patience to achieve.  Code still compiles even with one column of
+     text shifted.  This required even more patience.
+
+   - All rotated and shifted variants compiles without warnings.  This
+     involves various tweaks to satisfy cases where compiler is overly
+     protective, including but not limited to the "1125" at line 4 as
+     opposed to "1025", to satisfy -Waggresive-loop-optimizations.
+
+   - CRC32 of the code is embedded in the code itself.
+
+   - Process for writing prog.c is available in spoiler.html
+
+# Compatibility
+
+Nuko and the rotated tools accepts only ASCII files where each
+character maps to exactly one byte.  Also, end-of-line sequence is
+assumed to be LF only, as opposed to CR-LF.  All control characters
+are treated like normal printable characters, so files containing tabs
+will look weird after rotation, for example.
+
+Nuko has been verified to work with these compiler / OS combinations:
+
+   - gcc 4.8.4 on Linux
+   - gcc 4.9.2 on Linux
+   - gcc 6.1.0 on JS/Linux
+   - gcc 6.3.0 on Linux
+   - gcc 6.4.0 on Cygwin
+   - clang 3.5.0 on Linux
+   - clang 3.8.1 on Linux
+   - clang 5.0.1 on Cygwin
+   - tcc 0.9.25 on JS/Linux
+
+Nuko compiles without warnings with all compilers above, even with
+"-Wall -Wextra -pedantic" for gcc and clang.
+
+--------------------------------------------------------------------------------
+<!--
+(c) Copyright 1984-2018, [Leo Broukhis, Simon Cooper, Landon Curt Noll][judges] - All rights reserved
+This work is licensed under a [Creative Commons Attribution-ShareAlike 3.0 Unported License][cc].
+
+[judges]: http://www.ioccc.org/judges.html
+[cc]: http://creativecommons.org/licenses/by-sa/3.0/
+-->