Greatest Common Divisor

greatest_common_divisor.js

// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=ALDS1_1_B

// Test Case
// 54 20 => 2
// 147 105 => 21

var input = require('fs').readFileSync('/dev/stdin', 'utf8').trim().split(' ').map(Number);

function gcd(x, y) {
  if (y === 0) {
    console.log(x);
  } else {
    gcd(y, x % y);
  }
}

gcd(input[0], input[1]);