diff --git a/Bit-Manipulation/GrayCodes.js b/Bit-Manipulation/GrayCodes.js new file mode 100644 index 0000000000..c9ce8ecab9 --- /dev/null +++ b/Bit-Manipulation/GrayCodes.js @@ -0,0 +1,42 @@ +/** + * Generates a Gray code sequence for the given number of bits. + * @param {number} n - The number of bits in the Gray code sequence. + * @returns {number[]} - An array of Gray codes in binary format. + * @description + * Gray codes are binary sequences in which two successive values differ in only one bit. + * This function generates a Gray code sequence of length 2^n for the given number of bits. + * + * The algorithm follows these steps: + * + * 1. Initialize an array `grayCodes` to store the Gray codes. Start with [0, 1] for n = 1. + * 2. Iterate from 1 to n: + * a. Calculate `highestBit` as 2^i, where `i` is the current iteration index. + * b. Iterate in reverse order through the existing Gray codes: + * - For each Gray code `code`, add `highestBit | code` to `grayCodes`. + * - This operation flips a single bit in each existing code, creating new codes. + * 3. Return the `grayCodes` array containing the Gray codes in decimal representation. + * + *resources: [GFG](https://www.geeksforgeeks.org/generate-n-bit-gray-codes/) + * @example + * const n = 3; + * const grayCodes = generateGrayCodes(n); + * // grayCodes will be [0, 1, 3, 2, 6, 7, 5, 4] for n=3. + */ +function generateGrayCodes(n) { + if (n <= 0) { + return [0] + } + + const grayCodes = [0, 1] + + for (let i = 1; i < n; i++) { + const highestBit = 1 << i + for (let j = grayCodes.length - 1; j >= 0; j--) { + grayCodes.push(highestBit | grayCodes[j]) + } + } + + return grayCodes +} + +export { generateGrayCodes } diff --git a/Bit-Manipulation/test/GrayCodes.test.js b/Bit-Manipulation/test/GrayCodes.test.js new file mode 100644 index 0000000000..2e8c46cb8e --- /dev/null +++ b/Bit-Manipulation/test/GrayCodes.test.js @@ -0,0 +1,19 @@ +import { generateGrayCodes } from '../GrayCodes.js' + +describe('Gray codes', () => { + test.each([ + [0, [0b0]], + [1, [0b0, 0b1]], + [2, [0b00, 0b01, 0b11, 0b10]], + [3, [0b000, 0b001, 0b011, 0b010, 0b110, 0b111, 0b101, 0b100]], + [ + 4, + [ + 0b0000, 0b0001, 0b0011, 0b0010, 0b0110, 0b0111, 0b0101, 0b0100, 0b1100, + 0b1101, 0b1111, 0b1110, 0b1010, 0b1011, 0b1001, 0b1000 + ] + ] + ])('n = %i -> %j', (n, expected) => { + expect(generateGrayCodes(n)).toEqual(expected) + }) +})