gray_code.cpp

 
#include <bitset>  
#include <cassert>  
#include <iostream>  
#include <vector>  
 
namespace bit_manipulation {
namespace gray_code {
std::vector<std::bitset<32>> gray_code_generation(int n) {
    std::vector<std::bitset<32>> 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
 
static void test() { 
    std::vector<std::bitset<32>> gray_code_negative_1 = {};
 
    std::vector<std::bitset<32>> gray_code_0 = {};
 
    std::vector<std::bitset<32>> gray_code_1 = {
        std::bitset<32>(0), std::bitset<32>(1)
    };
 
    std::vector<std::bitset<32>> gray_code_2 = {
        std::bitset<32>(0), std::bitset<32>(1), std::bitset<32>(3), std::bitset<32>(2)
    };
 
    std::vector<std::bitset<32>> 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<std::bitset<32>> 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<std::bitset<32>> 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);
}
 
int main() {
    test();  //Run self-test implementation
    return 0;
}