Implemented PHP-LCS.

.gitattributes

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+.gitattributes export-ignore
+.gitignore export-ignore
+.travis.yml export-ignore
+phpunit.xml export-ignore
+phpunit.reports.xml export-ignore
+test export-ignore

.gitignore

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+test/report
+vendor

.travis.yml

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+language: php
+before_script:
+    - composer install --dev
+script: phpunit
+php:
+    - 5.3.3
+    - 5.3
+    - 5.4

LICENSE

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+Copyright © 2012 Erin Millard
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

@@ -1,4 +1,74 @@
-php-lcs
-=======
+# PHP-LCS
 
-Longest common subsequence implementation in PHP
+*An implementation of the 'longest common subsequence' algorithm for PHP.*
+
+## What is PHP-LCS?
+
+PHP-LCS is a PHP implementation of an algorithm to solve the 'longest common
+subsequence' problem.
+
+From [Wikipedia](http://en.wikipedia.org/wiki/Longest_common_subsequence_problem):
+
+> The **longest common subsequence (LCS) problem** is to find the longest
+> [subsequence](http://en.wikipedia.org/wiki/Subsequence) common to all
+> sequences in a set of sequences (often just two). Note that subsequence is
+> different from a substring, see
+> [substring vs. subsequence](http://en.wikipedia.org/wiki/Subsequence#Substring_vs._subsequence).
+> It is a classic [computer science](http://en.wikipedia.org/wiki/Computer_science)
+> problem, the basis of [file comparison](http://en.wikipedia.org/wiki/File_comparison)
+> programs such as [diff](http://en.wikipedia.org/wiki/Diff), and has
+> applications in [bioinformatics](http://en.wikipedia.org/wiki/Bioinformatics).
+
+## Usage
+
+```php
+<?php
+use Ezzatron\LCS\LCSSolver;
+
+$solver = new LCSSolver;
+
+$left = array(
+    'B',
+    'A',
+    'N',
+    'A',
+    'N',
+    'A',
+);
+$right = array(
+    'A',
+    'T',
+    'A',
+    'N',
+    'A',
+);
+$expectedLCS = array(
+    'A',
+    'A',
+    'N',
+    'A',
+);
+
+$LCS = $solver->longestCommonSubsequence(
+    $left,
+    $right
+);
+
+if ($LCS === $expectedLCS) {
+    echo 'LCS solver is working.';
+} else {
+    echo 'LCS solver is not working.';
+}
+// the above outputs 'LCS solver is working.'
+```
+
+## Code quality
+
+PHP-LCS strives to attain a high level of quality. A full test suite is
+available, and code coverage is closely monitored.
+
+### Latest revision test suite results
+[![Build Status](https://secure.travis-ci.org/ezzatron/php-lcs.png)](http://travis-ci.org/ezzatron/php-lcs)
+
+### Latest revision test suite coverage
+<http://ci.ezzatron.com/report/php-lcs/coverage/>

composer.json

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+{
+    "name": "ezzatron/php-lcs",
+    "description": "An implementation of the 'longest common subsequence' algorithm for PHP.",
+    "keywords": ["longest","common","subsequence","sequence","diff","algorithm"],
+    "homepage": "https://github.com/ezzatron/php-lcs",
+    "license": "MIT",
+    "authors": [
+        {
+            "name": "Erin Millard",
+            "email": "[email protected]",
+            "homepage": "http://ezzatron.com/"
+        }
+    ],
+    "require": {
+        "php": ">=5"
+    },
+    "autoload": {
+        "psr-0": {
+            "Ezzatron\\LCS": "src"
+        }
+    }
+}

phpunit.reports.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit
+    bootstrap="test/bootstrap.php"
+    strict="true"
+    mapTestClassNameToCoveredClassName="true"
+    convertErrorsToExceptions="true"
+    convertNoticesToExceptions="true"
+    convertWarningsToExceptions="true"
+    verbose="true"
+    colors="true"
+>
+    <testsuites>
+        <testsuite>
+            <directory>test/suite</directory>
+        </testsuite>
+    </testsuites>
+
+    <logging>
+        <log
+            type="coverage-clover"
+            target="test/report/coverage.xml"
+        />
+
+        <log
+            type="coverage-html"
+            target="test/report/coverage"
+            charset="UTF-8"
+            yui="true"
+            highlight="true"
+        />
+
+        <log
+            type="json"
+            target="test/report/logfile.json"
+        />
+
+        <log
+            type="tap"
+            target="test/report/logfile.tap"
+        />
+
+        <log
+            type="junit"
+            target="test/report/logfile.xml"
+            logIncompleteSkipped="false"
+        />
+
+        <log
+            type="testdox-html"
+            target="test/report/testdox.html"
+        />
+
+        <log
+            type="testdox-text"
+            target="test/report/testdox.txt"
+        />
+    </logging>
+
+    <filter>
+        <whitelist>
+            <directory>src</directory>
+        </whitelist>
+    </filter>
+</phpunit>

phpunit.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit
+    bootstrap="test/bootstrap.php"
+    strict="true"
+    mapTestClassNameToCoveredClassName="true"
+    convertErrorsToExceptions="true"
+    convertNoticesToExceptions="true"
+    convertWarningsToExceptions="true"
+    verbose="true"
+    colors="true"
+>
+    <testsuites>
+        <testsuite>
+            <directory>test/suite</directory>
+        </testsuite>
+    </testsuites>
+</phpunit>

src/Ezzatron/LCS/LCSSolver.php

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+<?php
+
+/*
+ * This file is part of the PHP-LCS package.
+ *
+ * Copyright © 2012 Erin Millard
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Ezzatron\LCS;
+
+class LCSSolver
+{
+    /**
+     * Returns the longest common subsequence of the given arrays.
+     *
+     * See http://en.wikipedia.org/wiki/Longest_common_subsequence_problem
+     *
+     * @param  array $left            The first array.
+     * @param  array $right           The second array.
+     * @param  array $additional,...  Any number of additional arrays.
+     *
+     * @return array The longest common subsequence.
+     */
+    public function longestCommonSubsequence(array $left, array $right)
+    {
+        if (func_num_args() > 2) {
+            $arguments = func_get_args();
+            array_splice(
+                $arguments,
+                0,
+                2,
+                array(
+                    $this->longestCommonSubsequence($left, $right)
+                )
+            );
+
+            return call_user_func_array(
+                array($this, 'longestCommonSubsequence'),
+                $arguments
+            );
+        }
+
+        $m = count($left);
+        $n = count($right);
+
+        // $a[$i][$j] = length of LCS of $left[$i..$m] and $right[$j..$n]
+        $a = array();
+
+        // compute length of LCS and all subproblems via dynamic programming
+        for ($i = $m - 1; $i >= 0; $i--) {
+            for ($j = $n - 1; $j >= 0; $j--) {
+                if ($left[$i] === $right[$j]) {
+                    $a[$i][$j] =
+                        (
+                            isset($a[$i + 1][$j + 1]) ?
+                            $a[$i + 1][$j + 1] :
+                            0
+                        ) +
+                        1
+                    ;
+                } else {
+                    $a[$i][$j] = max(
+                        (
+                            isset($a[$i + 1][$j]) ?
+                            $a[$i + 1][$j] :
+                            0
+                        ),
+                        (
+                            isset($a[$i][$j + 1]) ?
+                            $a[$i][$j + 1] :
+                            0
+                        )
+                    );
+                }
+            }
+        }
+
+        // recover LCS itself
+        $i = 0;
+        $j = 0;
+        $lcs = array();
+
+        while($i < $m && $j < $n) {
+            if ($left[$i] === $right[$j]) {
+                $lcs[] = $left[$i];
+
+                $i++;
+                $j++;
+            } elseif (
+                (
+                    isset($a[$i + 1][$j]) ?
+                    $a[$i + 1][$j] :
+                    0
+                ) >=
+                (
+                    isset($a[$i][$j + 1]) ?
+                    $a[$i][$j + 1] :
+                    0
+                )
+            ) {
+                $i++;
+            } else {
+                $j++;
+            }
+        }
+
+        return $lcs;
+    }
+}

test/bootstrap.php

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+<?php
+
+require __DIR__.'/../vendor/autoload.php';