chore: Merge pull request #759 from Aayushi-Mittal/powerOf2

Add code for checking whether given number is a power of 2 or not

Author: raklaptudirm

Bit-Manipulation/IsPowerOfTwo.js

@@ -0,0 +1,28 @@
+/*
+    author: @Aayushi-Mittal
+
+    This script will check whether the given
+    number is a power of two or not.
+
+    A number will be a power of two if only one bit is set and rest are unset.
+    This is true for all the cases except 01 because (2^0 = 1) which is not a power of 2.
+    For eg: 10 (2^1 = 2), 100 (2^2 = 4), 10000 (2^4 = 16)
+
+    Reference Link: https://www.hackerearth.com/practice/notes/round-a-number-to-the-next-power-of-2/
+
+    If we will subtract 1 from a number that is a power of 2 we will get it's 1's complement.
+    And we know that 1's complement is just opp. of that number.
+    So, (n & (n-1)) will be 0.
+
+    For eg:    (1000 & (1000-1)) 
+                1 0 0 0     // Original Number (8)
+                0 1 1 1     // After Subtracting 1 (8-1 = 7)
+                _______
+                0 0 0 0     // will become 0
+
+*/
+
+export const IsPowerOfTwo = (n) => {
+  if (n != 0 && (n & (n - 1)) == 0) return true
+  else return false
+}

Bit-Manipulation/test/IsPowerOfTwo.test.js

@@ -0,0 +1,26 @@
+import {IsPowerOfTwo} from '../IsPowerOfTwo'
+
+test('Check if 0 is a power of 2 or not:', () => {
+  const res = IsPowerOfTwo(0)
+  expect(res).toBe(false)
+})
+
+test('Check if 0 is a power of 2 or not:', () => {
+  const res = IsPowerOfTwo(1)
+  expect(res).toBe(false)
+})
+
+test('Check if 4 is a power of 2 or not:', () => {
+  const res = IsPowerOfTwo(4)
+  expect(res).toBe(true)
+})
+
+test('Check if 1024 is a power of 2 or not:', () => {
+  const res = IsPowerOfTwo(1024)
+  expect(res).toBe(true)
+})
+
+test('Check if 1025 is a power of 2 or not:', () => {
+  const res = IsPowerOfTwo(1025)
+  expect(res).toBe(false)
+})

DIRECTORY.md

@@ -10,6 +10,7 @@
 
 ## Bit-Manipulation
   * [BinaryCountSetBits](https://github.com/TheAlgorithms/Javascript/blob/master/Bit-Manipulation/BinaryCountSetBits.js)
+  * [IsPowerOfTwo](https://github.com/TheAlgorithms/Javascript/blob/master/Bit-Manipulation/IsPowerOfTwo.js)
   * [SetBit](https://github.com/TheAlgorithms/Javascript/blob/master/Bit-Manipulation/SetBit.js)
 
 ## Cache