Added implementation for euclidean algorithm in PHP (#430)

Author: PudottaPommin

contents/euclidean_algorithm/code/php/euclidean.php

@@ -0,0 +1,35 @@
+<?php
+declare(strict_types=1);
+
+function euclid_sub(int $a, int $b): int
+{
+    $a = abs($a);
+    $b = abs($b);
+
+    while ($a !== $b) {
+        if ($a > $b) {
+            $a = $a - $b;
+        } else {
+            $b = $b - $a;
+        }
+    }
+
+    return $a;
+}
+
+function euclid_mod(int $a, int $b): int
+{
+    $a = abs($a);
+    $b = abs($b);
+
+    while ($b !== 0) {
+        list($b, $a) = [$a % $b, $b];
+    }
+
+    return $a;
+}
+
+printf('Euclidean mod: %s', euclid_mod(64 * 67, 64 * 81));
+echo PHP_EOL;
+printf('Euclidean sub: %s', euclid_sub(128 * 12, 128 * 77));
+echo PHP_EOL;

contents/euclidean_algorithm/euclidean_algorithm.md

@@ -41,6 +41,8 @@ The algorithm is a simple way to find the *greatest common divisor* (GCD) of two
 [import:13-24, lang="nim"](code/nim/euclid_algorithm.nim)
 {% sample lang="f90" %}
 [import:1-19, lang="fortran"](code/fortran/euclidean.f90)
+{% sample lang="php" %}
+[import:4-18, lang="php"](code/php/euclidean.php)
 {% sample lang="factor" %}
 [import:1-13, lang="factor"](code/factor/euclid.factor)
 {% sample lang="ws" %}
@@ -102,6 +104,8 @@ Modern implementations, though, often use the modulus operator (%) like so
 [import:1-11, lang="nim"](code/nim/euclid_algorithm.nim)
 {% sample lang="f90" %}
 [import:21-34, lang="fortran"](code/fortran/euclidean.f90)
+{% sample lang="php" %}
+[import:20-30, lang="php"](code/php/euclidean.php)
 {% sample lang="factor" %}
 [import:15-25, lang="factor"](code/factor/euclid.factor)
 {% sample lang="ws" %}
@@ -168,6 +172,8 @@ The Euclidean Algorithm is truly fundamental to many other algorithms throughout
 [import, lang="nim" %](code/nim/euclid_algorithm.nim)
 {% sample lang="f90" %}
 [import, lang="fortran"](code/fortran/euclidean.f90)
+{% sample lang="php" %}
+[import, lang="php"](code/php/euclidean.php)
 {% sample lang="factor" %}
 [import, lang="factor"](code/factor/euclid.factor)
 {% sample lang="ws" %}