Merge pull request #141 from afonsocarlos/master

Add Greatest Common Divisor

Author: darwinz

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)

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);
+}

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));
+    }
 }