feat(gcd): Add gcd function (#125)

Author: ErdtR

src/gcd.js

@@ -0,0 +1,16 @@
+export default gcd
+
+/**
+ * This method return greatest common divisor for two numbers
+ * @param {Number} a - first number
+ * @param {Number} b - second number
+ * @return {Number} - greatest common divisor
+ */
+
+function gcd(a, b) {
+  if (!b) {
+    return a
+  }
+  
+  return gcd(b, a % b)
+}

src/index.js

@@ -42,6 +42,7 @@ import isNumeric from './is-numeric'
 import max from './max'
 import slugify from './slugify'
 import convertToRoman from './convertToRoman'
+import gcd from './gcd'
 
 export {
   isOdd,
@@ -88,4 +89,5 @@ export {
   max,
   slugify,
   convertToRoman,
+  gcd,
 }

test/gcd.test.js

@@ -0,0 +1,10 @@
+import test from 'ava'
+import {gcd} from '../src'
+
+test("Get gcd for two integers", t => {
+    const a = 4;
+    const b = 64;
+    const expected = 4;
+    const actual = gcd(a, b);
+    t.deepEqual(actual, expected)
+})