#include #include #include #include #include #include #include #include #include #include using std::cin; using std::cout; const char endl = '\n'; const int mod = 1e9 + 7; class AcAutomaton { private: struct node { int cnt; std::weak_ptr child[26], fail; node() : cnt(0) {} }; std::shared_ptr root; public: std::vector> nodes; std::unordered_map, int> nodes_id; AcAutomaton() : root(std::make_shared()), nodes({root}), nodes_id({{root, 0}}) {} void insert(std::string s) { auto cur = root; for (char c : s) { if (auto ptr = cur->child[c - 'a'].lock()) { cur = ptr; } else { ptr = std::make_shared(); cur->child[c - 'a'] = ptr; nodes_id[ptr] = nodes.size(); nodes.emplace_back(ptr); cur = ptr; } } cur->cnt++; } void build() { std::queue> q; for (int i = 0; i < 26; i++) { if (auto ptr = root->child[i].lock()) { q.emplace(ptr); ptr->fail = root; } else { root->child[i] = root; } } while (!q.empty()) { auto cur = q.front(); q.pop(); for (int i = 0; i < 26; i++) { if (auto ptr = cur->child[i].lock()) { auto cur_fail_ptr = cur->fail.lock(), cur_fail_ch_ptr = cur_fail_ptr->child[i].lock(); ptr->fail = cur_fail_ch_ptr ? cur_fail_ch_ptr : root; q.emplace(cur->child[i].lock()); } else { auto cur_fail_ptr = cur->fail.lock(), cur_fail_ch_ptr = cur_fail_ptr->child[i].lock(); cur->child[i] = cur_fail_ch_ptr ? cur_fail_ch_ptr : root; } } } } int query(std::string t) { int res = 0; std::shared_ptr cur = root; for (char c : t) { auto cur_ch_ptr = cur->child[c - 'a'].lock(); cur = cur_ch_ptr ? cur_ch_ptr : root; for (auto i = cur; i != nullptr && i->cnt != -1; i = i->fail.lock()) { res += i->cnt; i->cnt = -1; } } return res; } }; constexpr int binpow(int a, int b, int mod = ::mod) { int res = 1; a %= mod; while (b) { if (b & 1) res = static_cast(res) * a % mod; a = static_cast(a) * a % mod; b >>= 1; } return res; } void gauss(std::vector> &a, int n) { int r, c; for (r = c = 0; c <= n; c++) { int t = r; for (int i = r; i <= n; i++) { if (std::abs(a[i][c]) > std::abs(a[t][c])) t = i; } if (!a[t][c]) continue; std::swap(a[t], a[r]); for (int i = n + 1; i >= c; i--) { a[r][i] = static_cast(a[r][i]) * binpow(a[r][c], mod - 2) % mod; } for (int i = r + 1; i <= n; i++) { if (a[i][c] != 0) { for (int j = n + 1; j >= c; j--) { a[i][j] = ((a[i][j] - static_cast(a[i][c]) * a[r][j]) % mod + mod) % mod; } } } r++; } if (r <= n) throw std::logic_error("No Solution"); for (int i = n; i >= 0; i--) { for (int j = i + 1; j <= n; j++) { a[i][n + 1] = ((a[i][n + 1] - static_cast(a[i][j]) * a[j][n + 1]) % mod + mod) % mod; } } } const int inv_26 = binpow(26, mod - 2); int main() { std::ios::sync_with_stdio(false); cin.tie(nullptr); int t; cin >> t; while (t--) { int n; AcAutomaton ac; cin >> n; for (int i = 1; i <= n; i++) { std::string s; cin >> s; ac.insert(s); } ac.build(); std::vector> a(ac.nodes.size(), std::vector(ac.nodes.size() + 1)); for (int i = 0; i < ac.nodes.size(); i++) { a[i][i] = 1; if (ac.nodes[i]->cnt) continue; a[i].back() = 1; for (auto ch : ac.nodes[i]->child) { auto ptr = ch.lock(); a[i][ac.nodes_id[ptr]] = ((a[i][ac.nodes_id[ptr]] - inv_26) % mod + mod) % mod; } } gauss(a, ac.nodes.size() - 1); cout << static_cast(a[0].back()) * binpow(a[0][0], mod - 2) % mod << endl; } return 0; }