Add code for checking whether given number is a power of 2 or not #759

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	/*
	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
	}

26 changes: 26 additions & 0 deletions Bit-Manipulation/test/IsPowerOfTwo.test.js

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	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)
	})

1 change: 1 addition & 0 deletions DIRECTORY.md

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		## 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
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