From 2553639335f4f5885e61e6e5a7c9c0cdbda82735 Mon Sep 17 00:00:00 2001
From: Carlos Afonso <afonso.carlos.braga@gmail.com>
Date: Sun, 22 Oct 2023 21:35:08 +0100
Subject: [PATCH 1/2] Add Greatest Common Divisor

---
 Maths/GreatestCommonDivisor.php | 16 ++++++++++++++++
 tests/Maths/MathsTest.php       | 11 +++++++++++
 2 files changed, 27 insertions(+)
 create mode 100644 Maths/GreatestCommonDivisor.php

diff --git a/Maths/GreatestCommonDivisor.php b/Maths/GreatestCommonDivisor.php
new file mode 100644
index 00000000..54758359
--- /dev/null
+++ b/Maths/GreatestCommonDivisor.php
@@ -0,0 +1,16 @@
+<?php
+
+/**
+ * This function finds the greatest common division using Euclidean algorithm
+ * example: gcd(30, 24) => 6
+ * @param int $a
+ * @param int $b
+ * @return int
+ */
+function gcd(int $a, int $b): int
+{
+    if ($b == 0) {
+        return $a;
+    }
+    return gcd($b, $a % $b);
+}
diff --git a/tests/Maths/MathsTest.php b/tests/Maths/MathsTest.php
index 3d6f3008..e4222889 100644
--- a/tests/Maths/MathsTest.php
+++ b/tests/Maths/MathsTest.php
@@ -12,6 +12,7 @@
 require_once __DIR__ . '/../../Maths/FastExponentiation.php';
 require_once __DIR__ . '/../../Maths/Fibonacci.php';
 require_once __DIR__ . '/../../Maths/Fibonacci2.php';
+require_once __DIR__ . '/../../Maths/GreatestCommonDivisor.php';
 require_once __DIR__ . '/../../Maths/NeonNumber.php';
 require_once __DIR__ . '/../../Maths/PerfectSquare.php';
 require_once __DIR__ . '/../../Maths/Mean.php';
@@ -143,4 +144,14 @@ public function testMode()
         $this->assertEquals([1, 2, 3, 4, 5], mode(1, 2, 3, 4, 5));
         $this->assertEquals([2, 3, 4], mode(2, 2, 3, 3, 4, 4));
     }
+
+    public function testGreatestCommonDivisor()
+    {
+        $this->assertEquals(8, gcd(24, 16));
+        $this->assertEquals(5, gcd(10, 5));
+        $this->assertEquals(25, gcd(100, 75));
+        $this->assertEquals(6, gcd(12, 18));
+        $this->assertEquals(5, gcd(10, 15));
+        $this->assertEquals(3, gcd(9, 12));
+    }
 }

From 7bb741407983e022c78277069747eb8a3a05373d Mon Sep 17 00:00:00 2001
From: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Date: Sun, 22 Oct 2023 20:35:49 +0000
Subject: [PATCH 2/2] updating DIRECTORY.md

---
 DIRECTORY.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/DIRECTORY.md b/DIRECTORY.md
index d6df201e..e4f956d3 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -35,6 +35,7 @@
   * [Fastexponentiation](./Maths/FastExponentiation.php)
   * [Fibonacci](./Maths/Fibonacci.php)
   * [Fibonacci2](./Maths/Fibonacci2.php)
+  * [Greatestcommondivisor](./Maths/GreatestCommonDivisor.php)
   * [Mean](./Maths/Mean.php)
   * [Median](./Maths/Median.php)
   * [Mode](./Maths/Mode.php)