#include #ifdef DEBUG #include #else #define dump(...) ((void)0) #endif template bool chmin(T &a, const U &b){ return (a > b ? a = b, true : false); } template bool chmax(T &a, const U &b){ return (a < b ? a = b, true : false); } template void fill_array(T (&a)[N], const U &v){ std::fill((U*)a, (U*)(a + N), v); } template auto make_vector(const std::array &a, T value = T()){ static_assert(I >= 1); static_assert(N >= 1); if constexpr (I == 1){ return std::vector(a[N - I], value); }else{ return std::vector(a[N - I], make_vector(a, value)); } } template std::ostream& operator<<(std::ostream &s, const std::vector &a){ for(auto it = a.begin(); it != a.end(); ++it){ if(it != a.begin()) s << " "; s << *it; } return s; } template std::istream& operator>>(std::istream &s, std::vector &a){ for(auto &x : a) s >> x; return s; } std::string YesNo(bool value){return value ? "Yes" : "No";} std::string YESNO(bool value){return value ? "YES" : "NO";} std::string yesno(bool value){return value ? "yes" : "no";} template void putl(const T &value){ std::cout << value << "\n"; } template void putl(const Head head, const Tail &... tail){ std::cout << head << " "; putl(tail ...); } namespace haar_lib { template class modint { uint32_t val_; public: constexpr static auto mod(){return M;} constexpr modint(): val_(0){} constexpr modint(int64_t n){ if(n >= M) val_ = n % M; else if(n < 0) val_ = n % M + M; else val_ = n; } constexpr auto& operator=(const modint &a){val_ = a.val_; return *this;} constexpr auto& operator+=(const modint &a){ if(val_ + a.val_ >= M) val_ = (uint64_t)val_ + a.val_ - M; else val_ += a.val_; return *this; } constexpr auto& operator-=(const modint &a){ if(val_ < a.val_) val_ += M; val_ -= a.val_; return *this; } constexpr auto& operator*=(const modint &a){ val_ = (uint64_t)val_ * a.val_ % M; return *this; } constexpr auto& operator/=(const modint &a){ val_ = (uint64_t)val_ * a.inv().val_ % M; return *this; } constexpr auto operator+(const modint &a) const {return modint(*this) += a;} constexpr auto operator-(const modint &a) const {return modint(*this) -= a;} constexpr auto operator*(const modint &a) const {return modint(*this) *= a;} constexpr auto operator/(const modint &a) const {return modint(*this) /= a;} constexpr bool operator==(const modint &a) const {return val_ == a.val_;} constexpr bool operator!=(const modint &a) const {return val_ != a.val_;} constexpr auto& operator++(){*this += 1; return *this;} constexpr auto& operator--(){*this -= 1; return *this;} constexpr auto operator++(int){auto t = *this; *this += 1; return t;} constexpr auto operator--(int){auto t = *this; *this -= 1; return t;} constexpr static modint pow(int64_t n, int64_t p){ if(p < 0) return pow(n, -p).inv(); int64_t ret = 1, e = n % M; for(; p; (e *= e) %= M, p >>= 1) if(p & 1) (ret *= e) %= M; return ret; } constexpr static modint inv(int64_t a){ int64_t b = M, u = 1, v = 0; while(b){ int64_t t = a / b; a -= t * b; std::swap(a, b); u -= t * v; std::swap(u, v); } u %= M; if(u < 0) u += M; return u; } constexpr static auto frac(int64_t a, int64_t b){return modint(a) / modint(b);} constexpr auto pow(int64_t p) const {return pow(val_, p);} constexpr auto inv() const {return inv(val_);} friend constexpr auto operator-(const modint &a){return modint(M - a.val_);} friend constexpr auto operator+(int64_t a, const modint &b){return modint(a) + b;} friend constexpr auto operator-(int64_t a, const modint &b){return modint(a) - b;} friend constexpr auto operator*(int64_t a, const modint &b){return modint(a) * b;} friend constexpr auto operator/(int64_t a, const modint &b){return modint(a) / b;} friend std::istream& operator>>(std::istream &s, modint &a){s >> a.val_; return s;} friend std::ostream& operator<<(std::ostream &s, const modint &a){s << a.val_; return s;} template static auto div(){ static auto value = inv(N); return value; } explicit operator int32_t() const noexcept {return val_;} explicit operator int64_t() const noexcept {return val_;} }; } namespace haar_lib {} namespace solver { using namespace haar_lib; constexpr int m1000000007 = 1000000007; constexpr int m998244353 = 998244353; void init(){ std::cin.tie(0); std::ios::sync_with_stdio(false); std::cout << std::fixed << std::setprecision(12); std::cerr << std::fixed << std::setprecision(12); std::cin.exceptions(std::ios_base::failbit); } using mint = modint; void solve(){ int T; std::cin >> T; while(T--){ int N; std::cin >> N; std::vector A(N); std::cin >> A; mint ans = 0; for(int i = 0; i < N; ++i){ ans = (ans + A[i]) + (ans * A[i]); } std::cout << ans << "\n"; } } } int main(){ solver::init(); while(true){ try{ solver::solve(); std::cout << std::flush; std::cerr << std::flush; }catch(const std::istream::failure &e){ break; }catch(...){ break; } } return 0; }