freeCodeCamp/curriculum/challenges/english/08-coding-interview-prep/rosetta-code/greatest-common-divisor.english.md

title	id	challengeType
Greatest common divisor	5a23c84252665b21eecc7e82	5

Description

Write a function that returns the greatest common divisor of two integers.

Instructions

Tests

tests:
  - text: <code>gcd</code> should be a function.
    testString: assert(typeof gcd=='function','<code>gcd</code> should be a function.');
  - text: <code>gcd(24,36)</code> should return a number.
    testString: assert(typeof gcd(24,36)=='number','<code>gcd(24,36)</code> should return a number.');
  - text: <code>gcd(24,36)</code> should return <code>12</code>.
    testString: assert.equal(gcd(24,36),12,'<code>gcd(24,36)</code> should return <code>12</code>.');
  - text: <code>gcd(30,48)</code> should return <code>6</code>.
    testString: assert.equal(gcd(30,48),6,'<code>gcd(30,48)</code> should return <code>6</code>.');
  - text: <code>gcd(10,15)</code> should return <code>5</code>.
    testString: assert.equal(gcd(10,15),5,'<code>gcd(10,15)</code> should return <code>5</code>.');
  - text: <code>gcd(100,25)</code> should return <code>25</code>.
    testString: assert.equal(gcd(100,25),25,'<code>gcd(100,25)</code> should return <code>25</code>.');
  - text: <code>gcd(13,250)</code> should return <code>1</code>.
    testString: assert.equal(gcd(13,250),1,'<code>gcd(13,250)</code> should return <code>1</code>.');
  - text: <code>gcd(1300,250)</code> should return <code>50</code>.
    testString: assert.equal(gcd(1300,250),50,'<code>gcd(1300,250)</code> should return <code>50</code>.');

Challenge Seed

function gcd(a, b) {
  // Good luck!
}

Solution

function gcd(a, b) {
  return b==0 ? Math.abs(a):gcd(b, a % b);
}