diff --git a/bit_manipulation/gray_code.cpp b/bit_manipulation/gray_code.cpp new file mode 100644 index 00000000000..952758dea23 --- /dev/null +++ b/bit_manipulation/gray_code.cpp @@ -0,0 +1,113 @@ +/** + * @brief Program to generate n-bit [Gray + * code](https://en.wikipedia.org/wiki/Gray_code) + * + * @details + * Gray code is a binary numeral system + * where consecutive values differ in exactly 1 bit. + * The following code offers one of many possible Gray codes + * given some pre-determined number of bits. + */ + +#include /// for gray code representation +#include /// for assert +#include /// for IO operations +#include /// for vector data structure + +/** + * @namespace bit_manipulation + * @brief Bit manipulation algorithms + */ +namespace bit_manipulation { +/** + * @namespace gray_code + * @brief Generate n-bit Gray code + */ +namespace gray_code { +/** + * @brief The main function to generate n-bit Gray code + * + * @param n Number of bits + * @return A vector that stores the n-bit Gray code + */ +std::vector> gray_code_generation(int n) { + std::vector> gray_code = {}; // Initialise empty vector + + // No Gray codes for non-positive values of n + if (n <= 0) { + return gray_code; + } + + int total_codes = 1 << n; // Number of n-bit gray codes + + for (int i = 0; i < total_codes; i++) { + int gray_num = i ^ (i >> 1); // Gray code formula + gray_code.push_back(std::bitset<32>(gray_num)); // Store the value + } + + return gray_code; +} +} // namespace gray_code +} // namespace bit_manipulation + +/** + * @brief Self-test implementation + * + * @returns void + */ +static void test() { + std::vector> gray_code_negative_1 = {}; + + std::vector> gray_code_0 = {}; + + std::vector> gray_code_1 = { + std::bitset<32>(0), std::bitset<32>(1) + }; + + std::vector> gray_code_2 = { + std::bitset<32>(0), std::bitset<32>(1), std::bitset<32>(3), std::bitset<32>(2) + }; + + std::vector> gray_code_3 = { + std::bitset<32>(0), std::bitset<32>(1), std::bitset<32>(3), std::bitset<32>(2), + std::bitset<32>(6), std::bitset<32>(7), std::bitset<32>(5), std::bitset<32>(4) + }; + + std::vector> gray_code_4 = { + std::bitset<32>(0), std::bitset<32>(1), std::bitset<32>(3), std::bitset<32>(2), + std::bitset<32>(6), std::bitset<32>(7), std::bitset<32>(5), std::bitset<32>(4), + std::bitset<32>(12), std::bitset<32>(13), std::bitset<32>(15), std::bitset<32>(14), + std::bitset<32>(10), std::bitset<32>(11), std::bitset<32>(9), std::bitset<32>(8) + }; + + std::vector> gray_code_5 = { + std::bitset<32>(0), std::bitset<32>(1), std::bitset<32>(3), std::bitset<32>(2), + std::bitset<32>(6), std::bitset<32>(7), std::bitset<32>(5), std::bitset<32>(4), + std::bitset<32>(12), std::bitset<32>(13), std::bitset<32>(15), std::bitset<32>(14), + std::bitset<32>(10), std::bitset<32>(11), std::bitset<32>(9), std::bitset<32>(8), + std::bitset<32>(24), std::bitset<32>(25), std::bitset<32>(27), std::bitset<32>(26), + std::bitset<32>(30), std::bitset<32>(31), std::bitset<32>(29), std::bitset<32>(28), + std::bitset<32>(20), std::bitset<32>(21), std::bitset<32>(23), std::bitset<32>(22), + std::bitset<32>(18), std::bitset<32>(19), std::bitset<32>(17), std::bitset<32>(16) + }; + + // invalid values for n + assert(bit_manipulation::gray_code::gray_code_generation(-1) == gray_code_negative_1); + assert(bit_manipulation::gray_code::gray_code_generation(0) == gray_code_0); + + // valid values for n + assert(bit_manipulation::gray_code::gray_code_generation(1) == gray_code_1); + assert(bit_manipulation::gray_code::gray_code_generation(2) == gray_code_2); + assert(bit_manipulation::gray_code::gray_code_generation(3) == gray_code_3); + assert(bit_manipulation::gray_code::gray_code_generation(4) == gray_code_4); + assert(bit_manipulation::gray_code::gray_code_generation(5) == gray_code_5); +} + +/** + * @brief Main function + * @returns 0 on exit + */ +int main() { + test(); //Run self-test implementation + return 0; +}