#ifndef HIDDEN_IN_VISUAL_STUDIO // 無意味.折りたたむのが目的. // 警告の抑制 #define _CRT_SECURE_NO_WARNINGS // 使えるライブラリの読み込み #include #include // function #include // ifstream using namespace std; // 型名の短縮 using ll = long long; // -2^63 ~ 2^63 = 9 * 10^18(int は -2^31 ~ 2^31 = 2 * 10^9) using pii = pair; using pll = pair; using pil = pair; using pli = pair; using vi = vector; using vvi = vector; using vvvi = vector; using vl = vector; using vvl = vector; using vvvl = vector; using vb = vector; using vvb = vector; using vvvb = vector; using vc = vector; using vvc = vector; using vvvc = vector; using vd = vector; using vvd = vector; using vvvd = vector; template using priority_queue_rev = priority_queue, greater>; using Graph = vvi; // 定数の定義 const double PI = 3.14159265359; const double DEG = PI / 180.; // θ [deg] = θ * DEG [rad] const vi dx4 = { 1, 0, -1, 0 }; // 4 近傍(下,右,上,左) const vi dy4 = { 0, 1, 0, -1 }; const vi dx8 = { 1, 1, 0, -1, -1, -1, 0, 1 }; // 8 近傍 const vi dy8 = { 0, 1, 1, 1, 0, -1, -1, -1 }; const ll INFL = (ll)3e18; const int INF = (int)1e9; const double EPS = 1e-10; // 許容誤差に応じて調整 // 汎用マクロの定義 #define all(a) (a).begin(), (a).end() #define sz(x) ((int)(x).size()) #define Yes(b) {cout << ((b) ? "Yes" : "No") << endl;} #define rep(i, n) for(int i = 0, i##_len = int(n); i < i##_len; ++i) // 0 から n-1 まで昇順 #define repi(i, s, t) for(int i = int(s), i##_end = int(t); i <= i##_end; ++i) // s から t まで昇順 #define repir(i, s, t) for(int i = int(s), i##_end = int(t); i >= i##_end; --i) // s から t まで降順 #define repe(v, a) for(const auto& v : (a)) // a の全要素(変更不可能) #define repea(v, a) for(auto& v : (a)) // a の全要素(変更可能) #define repb(set, d) for(int set = 0; set < (1 << int(d)); ++set) // d ビット全探索(昇順) #define repbm(mid, set, d) for(int mid = set; mid < (1 << int(d)); mid = (mid + 1) | set) // set を含む部分集合の全探索(昇順) #define repbs(sub, set) for (int sub = set, bsub = 1; bsub > 0; bsub = sub, sub = (sub - 1) & set) // set の部分集合の全探索(降順) #define repbc(set, k, d) for (int set = (1 << k) - 1, lb, nx; set < (1 << n); lb = set & -set, nx = set + lb, set = (((set & ~nx) / lb) >> 1) | nx) // 大きさ k の部分集合の全探索 #define repp(a) sort(all(a)); for(bool a##_perm = true; a##_perm; a##_perm = next_permutation(all(a))) // a の順列全て(昇順) #define repit(it, a) for(auto it = (a).begin(); it != (a).end(); ++it) // イテレータを回す(昇順) #define repitr(it, a) for(auto it = (a).rbegin(); it != (a).rend(); ++it) // イテレータを回す(降順) // 汎用関数の定義 inline ll pow(ll n, int k) { ll v = 1; rep(i, k) v *= n; return v; } inline ll pow(int n, int k) { ll v = 1; rep(i, k) v *= n; return v; } template inline bool chmax(T& M, const T& x) { if (M < x) { M = x; return true; } return false; } // 最大値を更新(更新されたら true を返す) template inline bool chmin(T& m, const T& x) { if (m > x) { m = x; return true; } return false; } // 最小値を更新(更新されたら true を返す) // 入出力用の >>, << のオーバーロード template inline istream& operator>> (istream& is, pair& p) { is >> p.first >> p.second; return is; } template inline ostream& operator<< (ostream& os, const pair& p) { os << "(" << p.first << "," << p.second << ")"; return os; } template inline istream& operator>> (istream& is, tuple& t) { is >> get<0>(t) >> get<1>(t) >> get<2>(t); return is; } template inline ostream& operator<< (ostream& os, const tuple& t) { os << "(" << get<0>(t) << "," << get<1>(t) << "," << get<2>(t) << ")"; return os; } template inline istream& operator>> (istream& is, tuple& t) { is >> get<0>(t) >> get<1>(t) >> get<2>(t) >> get<3>(t); return is; } template inline ostream& operator<< (ostream& os, const tuple& t) { os << "(" << get<0>(t) << "," << get<1>(t) << "," << get<2>(t) << "," << get<3>(t) << ")"; return os; } template inline istream& operator>> (istream& is, vector& v) { repea(x, v) is >> x; return is; } template inline ostream& operator<< (ostream& os, const vector& v) { repe(x, v) os << x << " "; return os; } template inline ostream& operator<< (ostream& os, const set& s) { repe(x, s) os << x << " "; return os; } template inline ostream& operator<< (ostream& os, const unordered_set& s) { repe(x, s) os << x << " "; return os; } template inline ostream& operator<< (ostream& os, const map& m) { repe(p, m) os << p << " "; return os; } // 手元環境(Visual Studio) #ifdef _MSC_VER #define popcount (int)__popcnt // 全ビットにおける 1 の個数 #define popcountll (int)__popcnt64 inline int lsb(unsigned int n) { unsigned long i; _BitScanForward(&i, n); return i; } // 最下位ビットの位置(0-indexed) inline int msb(unsigned int n) { unsigned long i; _BitScanReverse(&i, n); return i; } // 最上位ビットの位置(0-indexed) ll gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; } #define dump(x) cerr << "[DEBUG]\n" << x << endl; // デバッグ出力用 #define dumpel(v) cerr << "[DEBUG]\n"; repe(x, v) {cerr << x << endl;} #define dumpeli(v) cerr << "[DEBUG]\n"; rep(i, sz(v)) {cerr << i << ": " << v[i] << endl;} // 提出用(GCC) #else #define popcount (int)__builtin_popcount #define popcountll (int)__builtin_popcountll #define lsb __builtin_ctz #define msb(n) (31 - __builtin_clz(n)) #define gcd __gcd #define dump(x) #define dumpel(v) #define dumpeli(v) #endif #endif // 無意味.折りたたむのが目的. //-----------------AtCoder 専用----------------- #include using namespace atcoder; using mint = modint1000000007; //using mint = modint998244353; //using mint = modint; // mint::set_mod(m); istream& operator>> (istream& is, mint& x) { ll tmp; is >> tmp; x = tmp; return is; } ostream& operator<< (ostream& os, const mint& x) { os << x.val(); return os; } using vm = vector; using vvm = vector; using vvvm = vector; //---------------------------------------------- //【階乗と二項係数(mint利用)】 /* * 十分大きな素数を法として,階乗,その逆数,二項係数を計算する. * * factorial_mint(n) : O(n) * n! までの階乗とその逆数を前計算する. * * factorial(n) : O(1) * n! を返す. * * factorial_inv(n) : O(1) * n! の逆元を返す. * * binomial(n, r) : O(1) * nCr を返す. * * multinomial(r) : O(|r|) * 多項係数 nC[r] を返す.(n = Σr) */ struct factorial_mint { // 階乗とその逆数の値を保持するテーブル vm fac; vm fac_inv; // n! までの階乗とその逆数を前計算しておく.O(n) factorial_mint(int n) { fac = vector(n + 1); fac[0] = 1; repi(i, 1, n) { fac[i] = fac[i - 1] * i; } fac_inv = vector(n + 1); fac_inv[n] = fac[n].inv(); repir(i, n - 1, 1) { fac_inv[i] = fac_inv[i + 1] * (i + 1); } fac_inv[0] = 1; } // n! を返す.O(1) mint factorial(int n) { return fac[n]; } // (n!)^(-1) を返す.O(1) mint factorial_inv(int n) { return fac_inv[n]; } // 二項係数 nCr を返す.O(1) mint binomial(int n, int r) { if (r < 0 || n - r < 0) { return 0; } return fac[n] * fac_inv[r] * fac_inv[n - r]; } // 多項係数 nC[r] を返す.O(|r|) mint multinomial(vi& r) { int len = sz(r); int sum = 0; rep(i, len) { sum += r[i]; } mint res = fac[sum]; repe(ri, r) { res *= fac_inv[ri]; } return res; } }; int main() { cout << fixed << setprecision(15); // 小数点以下の桁数の指定 int n; cin >> n; vi b(n); cin >> b; factorial_mint fm(n); mint res = 1; int bak = 0, len = 1; rep(i, n) { if (b[i] == -1) { len++; continue; } if (bak & (~b[i])) { cout << 0 << endl; return 0; } mint sum = 0; repi(j, 0, len - 1) { sum += mint(-1).pow(j) * fm.binomial(len, j) * (mint(2).pow(len - j) - 1).pow(popcount(b[i] - bak)) * mint(2).pow(len - j).pow(popcount(bak)); } res *= sum; bak = b[i]; len = 1; } cout << res << endl; }