RGB To Hex Conversion

• Time : $O(1)$
• Space : $O(1)$

class RGBToHex
{
public:
    static std::string rgb(int r, int g, int b);
};
std::string hex(int x) {
    x = std::clamp(x,0,255);
    auto toChar = [](int x) -> char {
        return x >= 10 ? 'A' + x - 10 : '0' + x;
    };
    return std::string{toChar(x / 16), toChar(x % 16)};
}
std::string RGBToHex::rgb(int r, int g, int b) {
    return hex(r) + hex(g) + hex(b);
}