45 lines
4.1 KiB
Markdown
45 lines
4.1 KiB
Markdown
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---
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title: Ninety-Nine Lisp Problems – P09 の解答
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author: kazu634
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date: 2010-11-22
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url: /2010/11/22/_1628/
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wordtwit_post_info:
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categories:
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- gauche
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- Lisp
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---
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<div class="section">
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<p>
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<a href="http://www.ic.unicamp.br/~meidanis/courses/mc336/2006s2/funcional/L-99_Ninety-Nine_Lisp_Problems.html" onclick="__gaTracker('send', 'event', 'outbound-article', 'http://www.ic.unicamp.br/~meidanis/courses/mc336/2006s2/funcional/L-99_Ninety-Nine_Lisp_Problems.html', 'L-99: Ninety-Nine Lisp Problems');" target="_blank">L-99: Ninety-Nine Lisp Problems</a>の問題を解答してみたよ。なんか、エレガントではないなぁ:
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</p>
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<pre class="syntax-highlight">
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<span class="synComment">;; P09 (**) Pack consecutive duplicates of list elements into sublists.</span>
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<span class="synComment">;; If a list contains repeated elements they should be placed in separate sublists.</span>
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<span class="synComment">;;</span>
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<span class="synComment">;; Example:</span>
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<span class="synComment">;; * (pack '(a a a a b c c a a d e e e e))</span>
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<span class="synComment">;; ((A A A A) (B) (C C) (A A) (D) (E E E E))</span>
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<span class="synSpecial">(</span>define <span class="synSpecial">(</span>pack-seed front sublist result l<span class="synSpecial">)</span>
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<span class="synSpecial">(</span><span class="synStatement">cond</span>
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[<span class="synSpecial">(</span><span class="synStatement">null</span>? l<span class="synSpecial">)</span> <span class="synSpecial">(</span><span class="synStatement">append</span> result <span class="synSpecial">(</span><span class="synStatement">list</span> sublist<span class="synSpecial">))</span>]
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[<span class="synSpecial">(</span><span class="synStatement">eq</span>? front <span class="synSpecial">(</span><span class="synStatement">car</span> l<span class="synSpecial">))</span> <span class="synSpecial">(</span>pack-seed front
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<span class="synSpecial">(</span><span class="synStatement">append</span> sublist
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<span class="synSpecial">(</span><span class="synStatement">list</span> front<span class="synSpecial">))</span>
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result
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<span class="synSpecial">(</span><span class="synStatement">cdr</span> l<span class="synSpecial">))</span>]
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[else <span class="synSpecial">(</span>pack-seed <span class="synSpecial">(</span><span class="synStatement">car</span> l<span class="synSpecial">)</span>
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<span class="synSpecial">(</span><span class="synStatement">list</span> <span class="synSpecial">(</span><span class="synStatement">car</span> l<span class="synSpecial">))</span>
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<span class="synSpecial">(</span><span class="synStatement">if</span> <span class="synSpecial">(</span><span class="synStatement">null</span>? result<span class="synSpecial">)</span>
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<span class="synSpecial">(</span><span class="synStatement">if</span> <span class="synSpecial">(</span><span class="synStatement">null</span>? sublist<span class="synSpecial">)</span>
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<span class="synSpecial">'()</span>
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<span class="synSpecial">(</span><span class="synStatement">append</span> result <span class="synSpecial">(</span><span class="synStatement">list</span> sublist<span class="synSpecial">)))</span>
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<span class="synSpecial">(</span><span class="synStatement">append</span> result <span class="synSpecial">(</span><span class="synStatement">list</span> sublist<span class="synSpecial">)))</span>
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<span class="synSpecial">(</span><span class="synStatement">cdr</span> l<span class="synSpecial">))</span>]<span class="synSpecial">))</span>
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<span class="synSpecial">(</span>define <span class="synSpecial">(</span>pack l<span class="synSpecial">)</span>
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<span class="synSpecial">(</span>pack-seed #f <span class="synSpecial">'()</span> <span class="synSpecial">'()</span> l<span class="synSpecial">))</span>
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<span class="synSpecial">(</span>pack <span class="synSpecial">'(</span>a a a a b c c a a d e e e e<span class="synSpecial">))</span>
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</pre>
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</div>
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