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25 changes: 25 additions & 0 deletions bit_manipulation/is_power_of_2.ts
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/**
* This code will check whether the given number is a power of two or not.
* @author dev-madhurendra<https://github.com/dev-madhurendra>
* @explanation

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)

@see: 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
* @param {number}
* @returns {boolean}
*/

export const isPowerOfTwo = (n: number): boolean => n > 0 && (n & (n - 1)) === 0
14 changes: 14 additions & 0 deletions bit_manipulation/test/is_power_of_2.test.ts
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import { isPowerOfTwo } from "../is_power_of_2"


describe('IsPowerOfTwo' , () => {
it.each([
[0, false],
[1, true],
[4, true],
[1024, true],
[1025, false],
])('Check if %i is a power of 2 or not', (number, expected) => {
expect(isPowerOfTwo(number)).toBe(expected);
});
})