diff --git a/Bit-Manipulation/SetBit.js b/Bit-Manipulation/SetBit.js new file mode 100644 index 0000000000..f7774dd54f --- /dev/null +++ b/Bit-Manipulation/SetBit.js @@ -0,0 +1,31 @@ +/* + * Setting Bit: https://www.geeksforgeeks.org/set-k-th-bit-given-number/ + * + * To set any bit we use bitwise OR (|) operator. + * + * Bitwise OR (|) compares the bits of the 32 + * bit binary representations of the number and + * returns a number after comparing each bit. + * + * 0 | 0 -> 0 + * 0 | 1 -> 1 + * 1 | 0 -> 1 + * 1 | 1 -> 1 + * + * In-order to set kth bit of a number (where k is the position where bit is to be changed) + * we need to shift 1 k times to its left and then perform bitwise OR operation with the + * number and result of left shift performed just before. + * + * References: + * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_OR + */ + +/** + * @param {number} number + * @param {number} bitPosition - zero based. + * @return {number} + */ + +export const setBit = (number, bitPosition) => { + return number | (1 << bitPosition) +} diff --git a/Bit-Manipulation/test/SetBit.test.js b/Bit-Manipulation/test/SetBit.test.js new file mode 100644 index 0000000000..0fc0a1d4b8 --- /dev/null +++ b/Bit-Manipulation/test/SetBit.test.js @@ -0,0 +1,21 @@ +import { setBit } from '../SetBit' + +test('Set bit number 0 in 1:', () => { + const setBitPos = setBit(1, 0) + expect(setBitPos).toBe(1) +}) + +test('Set bit number 0 in 2:', () => { + const setBitPos = setBit(2, 0) + expect(setBitPos).toBe(3) +}) + +test('Set bit number 1 in 10:', () => { + const setBitPos = setBit(10, 1) + expect(setBitPos).toBe(10) +}) + +test('Set bit number 2 in 10:', () => { + const setBitPos = setBit(10, 2) + expect(setBitPos).toBe(14) +})