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 Well-rounded Hash</title>
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</head>
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<body>
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<h1>Most Well-rounded Hash</h1>
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<p>Qiming Hou <a href="mailto:hqm03ster@gmail.com">hqm03ster@gmail.com</a><br>
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<a href="http://www.houqiming.net/">http://www.houqiming.net/</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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echo IOCCC | ./prog
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</code></pre>
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<h3>Try:</h3>
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<pre><code>echo "" | ./prog
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</code></pre>
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<h3>Selected Judges Remarks:</h3>
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<p>A good start for understanding this entry might be
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https://www.ietf.org/rfc/rfc1321.txt. How does it compute this using only a
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single looping construct? The original reference source code for this
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algorithm is about 355 lines of code, yet this entry is only 199 lines with
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one statement per line and it isn’t using lots of macro expansion tricks like
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the reference code!</p>
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<p>Some things that make you go, “huh?”</p>
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<pre><code>./prog < prog.c | cut -c-5
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./prog < Makefile | cut -c-4
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</code></pre>
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<p>How are those values magically returned?</p>
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<p>What happens with a large file? Something over 256K</p>
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<pre><code>./prog < large_file
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</code></pre>
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<p>Where does that message come from?</p>
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<h2>Author’s comments:</h2>
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<p>This looks like a normal C program.</p>
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<p>Almost everything is a double.</p>
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<p>There are tell-tale signs like <code>pow(2,(?/12))</code> and <code>exp(-?*?)</code> (names redacted). You can also find a bunch of cosines and polynomial evaluations.</p>
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<p>It looks like a ????? ???????????, right?</p>
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<p>Run and find out.</p>
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<h3>Why obfuscated</h3>
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<p>Some poor scripting folks only have access to doubles (Jav?script, L?a, BA?IC, etc.).</p>
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<p>As a C programmer, I feel obliged to show a gesture of sympathy, to experience their pain and provide an answer.</p>
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<p>Except when absolutely necessary (<code>printf</code>, <code>int main()</code>, array indexing), there isn’t a single integer. Even <code>getchar()</code> and <code>EOF</code> are immediately converted.</p>
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<p>Since <code>bool</code> counts as an integer type too, there is no boolean either. No comparison, no <code>if</code>, no <code>?:</code>, no <code>||</code> <code>&&</code>. Everything is done in a single loop that terminates on printf. Straight up arithmetic.</p>
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<p><code>floor</code> and <code>ceil</code> are technically double-to-double functions, but they feel like cheating. Yes <code>cos</code>, no <code>floor</code>.</p>
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<h3>Limitations</h3>
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<p>Hard requirements:</p>
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<ul>
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<li><p>The platform must implement the <code>double</code> type as IEEE754-compliant 64-bit floating point numbers. The 80-bit intermediate format used by x87 is considered as an violation of this. The code should print an error message on such platforms.</p></li>
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<li><p>The program must start with the CPU / FPU in round-to-nearest mode.</p></li>
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</ul>
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<p>Soft requirements:</p>
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<ul>
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<li><p>The compiler must respect <code>volatile</code>. The code is formatted to warn about that, though.</p></li>
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<li><p>The printed result is only correct on little-endian machines. The program takes care to warn about this issue after printing an incorrect big-endian result. Error messages become garbled, though.</p></li>
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</ul>
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<p>Tested platforms:</p>
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<ul>
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<li>Linux 3.18.7, Rasperberry Pi 2, clang 3.0-6.2, (works)</li>
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<li>Linux 3.18.7, Rasperberry Pi 2, gcc 4.6.3, (works)</li>
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<li>Mac OS X 10, x64, Apple LLVM version 6.1.0 (clang-602.0.53), (works)</li>
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<li>Windows 8.1, x86, MSVC 2012 (works)</li>
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<li>Windows 8.1, x64, MSVC 2012 (works)</li>
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<li>Windows 8.1, x86, MinGW gcc 4.6.2 (fails, prints error message)</li>
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<li>Windows 8.1, x86, MinGW gcc 4.6.2 with -msse2 -mfpmath=sse (works)</li>
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</ul>
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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 1984-2016,
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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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