#include static constexpr auto pattern = ctll::fixed_string(".?|(..+?)\\g{1}+"); constexpr bool is_prime(std::string_view input) { return !ctre::match(input); } int main() { static_assert(!is_prime("")); static_assert(!is_prime("a")); static_assert( is_prime("aa")); static_assert( is_prime("aaa")); static_assert(!is_prime("aaaa")); static_assert( is_prime("aaaaa")); static_assert(!is_prime("aaaaaa")); static_assert( is_prime("aaaaaaa")); static_assert(!is_prime("aaaaaaaa")); static_assert(!is_prime("aaaaaaaaa")); static_assert(!is_prime("aaaaaaaaaa")); static_assert( is_prime("aaaaaaaaaaa")); }