Remove hint.html and index.html
As per discussions on GitHub the index.html and hint.html files should be deleted in favour of README.md files (from any .text/.txt/.markdown/.md files which will be turned into README.md in an upcoming commit).
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta name="GENERATOR" content="mkd2html 2.1.5a DL=DISCOUNT">
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<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=utf-8">
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<link rel="stylesheet"
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type="text/css"
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href="../hint.css">
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<title>Most shifty</title>
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</head>
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<body>
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<h1>Most shifty</h1>
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<p>Don Yang<br>
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<a href="http://uguu.org/">http://uguu.org/</a></p>
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<h2>Judges' comments:</h2>
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<h3>To use:</h3>
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<pre><code>make
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more generated1.c
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more generated2.c
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more generated3.c
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</code></pre>
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<h3>Try:</h3>
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<pre><code>make
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./left < prog.c
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./right < prog.c
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./left < prog.c | ./left
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./shift < prog.c
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./msg0
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./msg1
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./msg2
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</code></pre>
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<h3>Selected Judges Remarks:</h3>
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<p>Code should be readable in any direction! This tool will help you rotate your
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code so you don’t have to stare at it sideways or even upside down. Rotating
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this program left and recompiling will reveal other tools including a right rotate
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and a shift program.</p>
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<p>Strange things happen when the world is upside down! It is entirely possible
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that this is remark is completely misleading.</p>
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<p>What exactly does the shift program do?</p>
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<p>Like a great sliding puzzle (hint) this entry has 6 more programs that will
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reveal messages and one more tool that can be used to reveal the final
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message hidden in the original source. All of these can be created using
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combinations of ./left, ./right and ./shift and the additionally generated
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programs.</p>
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<p>The final message can be revealed using</p>
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<pre><code>./msg9 < prog.c
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</code></pre>
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<p>But what combinations will generate ./msg3, ./msg4, ./msg5, ./msg6, ./msg7,
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./msg8 and finally ./msg9?</p>
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<h2>Author’s comments:</h2>
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<h1>Tools usage</h1>
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<p>Nuko is a text rotator: given some text in stdin, Nuko will write the
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same text to stdout, but rotated 90 degrees counterclockwise.</p>
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<pre><code>gcc prog.c -o left
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./left < input.txt > rotated_counterclockwise.txt
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</code></pre>
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<p>Due to static memory allocation, only the first 1K columns by 1K rows
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are rotated, the rest are silently ignored. But fear not, a separate
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tool with dynamic memory allocation is included:</p>
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<pre><code>./left < prog.c > r1.c
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gcc r1.c -o right
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./right < input.txt > rotated_clockwise.txt
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</code></pre>
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<p>For variety, this second tool rotates clockwise instead of
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counterclockwise. Also, it can handle files larger than 1024x1024,
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depending on how much memory you got.</p>
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<p>Of course we wouldn’t stop with just two rotations, if we continue to
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rotate counterclockwise once more, we get another program. This
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program outputs a single message to stdout, which is the name of the
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series that Nuko came from.</p>
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<pre><code>./left < prog.c | ./left > r2.c
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gcc r2.c -o msg0
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./msg0
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</code></pre>
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<p>There is one final rotation, which produces a tool that removes
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leading whitespaces:</p>
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<pre><code>./left < prog.c | ./left | ./left > r3.c
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gcc r3.c -o shift
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./shift < input.txt > no_leading_space.txt
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</code></pre>
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<p>Where this might be useful, besides ruining the formatting of certain
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files, is that it completes the set of tools needed to solve the
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puzzle that is embedded in prog.c</p>
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<h1>Puzzle box</h1>
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<p>Notice how the edges of prog.c contain two notches. By rotating
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prog.c and removing leading space, the code would be shifted one space
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toward one of those notches (and creating a new notch on the other
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side). This shifted code behaves slightly different from the original
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program. For example, here are two more messages that can be
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produced:</p>
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<pre><code>./shift < prog.c | ./right > msg1.c && gcc msg1.c -o msg1 && ./msg1
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./shift < prog.c | ./left > msg2.c && gcc msg2.c -o msg2 && ./msg2
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</code></pre>
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<p>In total, there are 9 embedded strings that can be produced via a
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sequence of rotates and shifts, one of which can be used to extract
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the 10th final string from prog.c. The intent is to simulate those
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wooden puzzle boxes that can be opened by pushing and shifting various
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well-concealed seams. Thus, finding the correct sequence of rotates
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and shifts is left as an exercise to the reader (but if you are really
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lazy, just read the Makefile).</p>
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<p>Source code for all the tools needed to solve this puzzle are embedded
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in prog.c, all you need is a C compiler.</p>
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<h1>Features</h1>
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<ul>
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<li><p> Code compiles when rotated 4 ways. This required a bit of
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patience to achieve. Code still compiles even with one column of
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text shifted. This required even more patience.</p></li>
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<li><p> All rotated and shifted variants compiles without warnings. This
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involves various tweaks to satisfy cases where compiler is overly
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protective, including but not limited to the “1125” at line 4 as
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opposed to “1025”, to satisfy -Waggresive-loop-optimizations.</p></li>
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<li><p> CRC32 of the code is embedded in the code itself.</p></li>
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<li><p> Process for writing prog.c is available in spoiler.html</p></li>
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</ul>
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<h1>Compatibility</h1>
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<p>Nuko and the rotated tools accepts only ASCII files where each
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character maps to exactly one byte. Also, end-of-line sequence is
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assumed to be LF only, as opposed to CR-LF. All control characters
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are treated like normal printable characters, so files containing tabs
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will look weird after rotation, for example.</p>
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<p>Nuko has been verified to work with these compiler / OS combinations:</p>
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<ul>
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<li> gcc 4.8.4 on Linux</li>
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<li> gcc 4.9.2 on Linux</li>
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<li> gcc 6.1.0 on JS/Linux</li>
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<li> gcc 6.3.0 on Linux</li>
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<li> gcc 6.4.0 on Cygwin</li>
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<li> clang 3.5.0 on Linux</li>
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<li> clang 3.8.1 on Linux</li>
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<li> clang 5.0.1 on Cygwin</li>
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<li> tcc 0.9.25 on JS/Linux</li>
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</ul>
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<p>Nuko compiles without warnings with all compilers above, even with
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“-Wall -Wextra -pedantic” for gcc and clang.</p>
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<hr />
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<TABLE><TR>
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<TD><a rel="license" href="http://creativecommons.org/licenses/by-sa/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-sa/3.0/88x31.png" /></a></TD>
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<TD><P>© Copyright 1984-2018,
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<A HREF="/judges.html">Leo Broukhis, Simon Cooper, Landon Curt Noll</A>
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- All rights reserved<BR>
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This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-sa/3.0/">Creative Commons Attribution-ShareAlike 3.0 Unported License</a>.</P></TD>
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<TD> <!--<a href="http://validator.w3.org/check?uri=referer"><img src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01 Transitional" height="31" width="88"></a>--></TD>
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</TR></TABLE>
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</body>
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</html>
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