added get Divisors and Fisher Yates Algorithm

src/algorithms/math/divisors.js

@@ -0,0 +1,21 @@
+/**
+ * Calculates the list of divisors of a number in sorted order
+ * @param  {Number} n number
+ * @return {Array}   Array of Divisors
+ * Time Complexity = O(n ^ 0.5)
+ */
+const getDivisors = (n) => {
+  let divisors = [];
+  if (n < 1) return [];
+  const tempArray = [];
+  for (let i = 1; i * i <= n; i += 1) {
+    if (n % i === 0) {
+      divisors.push(i);
+      if (i !== n / i) tempArray.push(n / i);
+    }
+  }
+  divisors = divisors.concat(tempArray.reverse());
+  return divisors;
+};
+
+module.exports = getDivisors;

src/algorithms/math/fisher_Yates.js

@@ -0,0 +1,22 @@
+/**
+ * Shuffle array in-place using Fisher-Yates Algorithm
+ * @param  {Array} array Array to be shuffled
+ * @return {Array}   Shuffled Array
+ *
+ */
+const Shuffle = (array) => {
+  let currentIndex = array.length;
+  let randomIndex;
+
+  while (currentIndex !== 0) {
+    randomIndex = Math.floor(Math.random() * currentIndex);
+    currentIndex -= 1;
+
+    [array[currentIndex], array[randomIndex]] = [
+      array[randomIndex], array[currentIndex]];
+  }
+
+  return array;
+};
+
+module.exports = Shuffle;

src/algorithms/math/index.js

@@ -3,8 +3,12 @@ const gcd = require('./gcd');
 const fastexp = require('./fast_exp');
 const lcm = require('./lcm');
 const modularInverse = require('./modular_inverse');
+const Shuffle = require('./fisher_Yates');
+const getDivisors = require('./divisors');
 
 module.exports = {
+  Shuffle,
+  getDivisors,
   extendedEuclidean,
   gcd,
   fastexp,

test/algorithms/math/divisors.js

@@ -0,0 +1,24 @@
+/* eslint-env mocha */
+const getDivisors = require('../../../src').algorithms.math.getDivisors;
+
+const assert = require('assert');
+
+describe('Divisors', () => {
+  it('should return empty array for number 0', () => {
+    assert.deepEqual(getDivisors(0), []);
+  });
+
+  it('should return [] for negative numbers ', () => {
+    assert.deepEqual(getDivisors(-3), []);
+  });
+
+  it('should return [1] for 1', () => {
+    assert.deepEqual(getDivisors(1), [1]);
+  });
+
+  it('should return divisors of a number', () => {
+    assert.deepEqual(getDivisors(100), [1, 2, 4, 5, 10, 20, 25, 50, 100]);
+    assert.deepEqual(getDivisors(10), [1, 2, 5, 10]);
+    assert.deepEqual(getDivisors(125), [1, 5, 25, 125]);
+  });
+});

test/algorithms/math/fisherYates.js

@@ -0,0 +1,15 @@
+/* eslint-env mocha */
+const Shuffle = require('../../../src').algorithms.math.Shuffle;
+
+const assert = require('assert');
+
+describe('Shuffle', () => {
+  it('should return empty array for an empty array', () => {
+    assert.deepEqual(Shuffle([]), []);
+  });
+
+  it('length of both the array should be same ', () => {
+    const arr = [1, 2, 3];
+    assert.deepEqual(Shuffle(arr).length, 3);
+  });
+});