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<?xml version="1.0" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
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<title>Perl Weekly Challenge #42 Task #2, Balanced Brackets</title>
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<body>
<table border="0" width="100%" cellspacing="0" cellpadding="3">
<tr><td class="_podblock_" valign="middle">
<big><strong><span class="_podblock_"> Perl Weekly Challenge #42 Task #2, Balanced Brackets</span></strong></big>
</td></tr>
</table>
<ul id="index">
<li><a href="#Perl-Weekly-Challenge-42-Task-2:-Balanced-Brackets">Perl Weekly Challenge #42 Task #2: Balanced Brackets</a></li>
<li><a href="#SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#Definition-Task-2:-Balanced-Brackets">Definition Task #2: Balanced Brackets</a></li>
<li><a href="#Perl5-and-Perl6">Perl5 and Perl6</a>
<ul>
<li><a href="#Perl-Example-Execution">Perl Example Execution</a></li>
<li><a href="#Source-Code">Source Code</a></li>
</ul>
</li>
<li><a href="#Python">Python</a>
<ul>
<li><a href="#Python-Example-Execution">Python Example Execution</a></li>
<li><a href="#Source-Code-Python">Source Code Python</a></li>
<li><a href="#Python-help">Python help</a></li>
</ul>
</li>
<li><a href="#AUTHOR">AUTHOR</a></li>
</ul>
<h1 id="Perl-Weekly-Challenge-42-Task-2:-Balanced-Brackets">Perl Weekly Challenge #42 Task #2: Balanced Brackets</h1>
<p>This Task "Balanced Brackets" I solved in 3 languages: Perl5, Perl6 and Python. My personal aim here is also to learn Perl6 and Python beside the eager in solving the Tasks in Perl5.</p>
<p>Some highlights:</p>
<ul>
<li><p>Perl5, Perl6 and Python solution.</p>
</li>
<li><p>Recursive function call.</p>
</li>
<li><p>do-while, do-repeat or while-if-break as DO-WHILE loop.</p>
</li>
<li><p>random integer number generation.</p>
</li>
</ul>
<h2> Download and References </h2>
<b>Download File:</b><a href="ch-2.pl" download> Perl5 Solution PWC #42 Task #2 ch-2.pl</a><br>
<b>Download File:</b><a href="ch-2.p6" download> Perl6 Solution PWC #42 Task #2 ch-2.p6</a><br>
<b>Download File:</b><a href="ch-2.py" download> Python Solution PWC #42 Task #2 ch-2.py</a><br>
<br>
<h1 id="SYNOPSIS">SYNOPSIS</h1>
<pre><code> # ./ch-2.pl - Execution of program
# ./ch-2.p6 - Execution of program
# ./ch-2.py - Execution of program
# perldoc ch-2.pod - POD</code></pre>
<h1 id="Definition-Task-2:-Balanced-Brackets">Definition Task #2: Balanced Brackets</h1>
<p>Write a script to generate a string with random number of ( and ) brackets. Then make the script validate the string if it has balanced brackets.</p>
<pre><code> For example:
() - OK
(()) - OK
)( - NOT OK
())() - NOT OK</code></pre>
<h1 id="Perl5-and-Perl6">Perl5 and Perl6</h1>
<p>How does the program work? Within a loop, that is left when some <b>Balanced Brackets</b> are found, a random number of brackets is created with the function <code>create_brackets()</code>. Than the bracket string is verified if it is <b>Balanced Brackets</b> in the function <code>balanced_brackets()</code>. The function <code>balanced_brackets()</code> is called recursively as long as a pair of brackets can be found with search/replace.</p>
<h2 id="Perl-Example-Execution">Perl Example Execution</h2>
<pre><code> # ./ch-2.pl
ch-2.pl (Version 1.0) PWC #42 Task #2: Balanced Brackets
(()))()))) - NOT OK
() - OK</code></pre>
<h2 id="Source-Code">Source Code</h2>
<p>The code for Perl5 and Perl6 are similar, only the differences in the language. Let me mention some of the differences between <b>Perl5 / Perl6</b>:</p>
<ul>
<li><p>for() / loop (), Remember the blank in Perl6.</p>
</li>
<li><p>.= / ~=, Assignment of a String.</p>
</li>
<li><p>int(rand(2)) / Int(2.rand), Create a random integer.</p>
</li>
<li><p>if() / if (), Again the blank after the statement, in Perl6 brackets directly after the keyword means to call a function.</p>
</li>
<li><p>sub balanced_brackets { my $str = shift; ... } sub balanced_brackets ($arg) { ... } Different function call syntax.</p>
</li>
<li><p>=~ / ~~, for applying the search/replace on a scalar.</p>
</li>
<li><p>do {} while() / repeat {} while (), A do-while loop becomes repeat-while.</p>
</li>
</ul>
<table class=code><tr><td class=code>
<pre class=code><div class=t> Perl5 </div>
1 <span class="synPreProc">#!/usr/bin/perl</span>
2
3 <span class="synStatement">use strict</span>;
4 <span class="synStatement">use warnings</span>;
5
6 <span class="synStatement">print</span> <span class="synConstant">"ch-2.pl (Version 1.0) PWC #42 Task #2: Balanced Brackets</span><span class="synSpecial">\n</span><span class="synConstant">"</span>;
7
8 <span class="synStatement">sub </span><span class="synIdentifier">create_brackets </span>{
9 <span class="synStatement">my</span> (<span class="synIdentifier">$nr</span>) = <span class="synIdentifier">@_</span>;
10 <span class="synStatement">my</span> <span class="synIdentifier">$s</span>;
11 <span class="synStatement">for</span>( <span class="synStatement">my</span> <span class="synIdentifier">$i</span>=<span class="synConstant">0</span>; <span class="synIdentifier">$i</span><=<span class="synIdentifier">$nr</span>; <span class="synIdentifier">$i</span>++ ) {
12 <span class="synStatement">my</span> <span class="synIdentifier">$br</span> = <span class="synStatement">int</span>(<span class="synStatement">rand</span>(<span class="synConstant">2</span>));
13 <span class="synStatement">if</span>(<span class="synIdentifier">$br</span>) { <span class="synIdentifier">$s</span> .= <span class="synConstant">")"</span>; } <span class="synStatement">else</span> { <span class="synIdentifier">$s</span> .= <span class="synConstant">"("</span>; }
14 }
15 <span class="synStatement">return</span> <span class="synIdentifier">$s</span>;
16 }
17
18 <span class="synStatement">my</span> <span class="synIdentifier">$ok</span>;
19 <span class="synStatement">do</span> {
20 <span class="synStatement">my</span> <span class="synIdentifier">$nr</span> = <span class="synStatement">int</span>(<span class="synStatement">rand</span>(<span class="synConstant">10</span>));
21 <span class="synStatement">my</span> <span class="synIdentifier">$str</span> = create_brackets(<span class="synIdentifier">$nr</span>);
22 <span class="synIdentifier">$ok</span> = balanced_brackets(<span class="synIdentifier">$str</span>);
23 <span class="synStatement">my</span> <span class="synIdentifier">$rs</span> = <span class="synConstant">"NOT OK"</span>;
24 <span class="synIdentifier">$rs</span> = <span class="synConstant">"OK"</span> <span class="synStatement">if</span> <span class="synIdentifier">$ok</span>;
25 <span class="synStatement">print</span> <span class="synIdentifier">$str</span>, <span class="synConstant">" - "</span>, <span class="synIdentifier">$rs</span>, <span class="synConstant">"</span><span class="synSpecial">\n</span><span class="synConstant">"</span>;
26 } <span class="synStatement">while</span>( ! <span class="synIdentifier">$ok</span> );
27
28 <span class="synStatement">sub </span><span class="synIdentifier">balanced_brackets </span>{
29 <span class="synStatement">my</span> <span class="synIdentifier">$str</span> = <span class="synStatement">shift</span>;
30 <span class="synStatement">my</span> <span class="synIdentifier">$found</span> = <span class="synIdentifier">$str</span> =~ <span class="synStatement">s/</span><span class="synSpecial">\(\)</span><span class="synStatement">//</span>;
31 <span class="synStatement">my</span> <span class="synIdentifier">$ok</span>;
32 <span class="synStatement">if</span>(<span class="synIdentifier">$found</span>) {
33 <span class="synIdentifier">$ok</span> = balanced_brackets(<span class="synIdentifier">$str</span>);
34 <span class="synStatement">return</span> <span class="synIdentifier">$ok</span>;
35 }
36 <span class="synStatement">else</span> {
37 <span class="synStatement">if</span>( <span class="synIdentifier">$str</span>=~<span class="synStatement">/</span><span class="synSpecial">\(</span><span class="synConstant">|</span
|
