#include <iostream> #include <vector> #include <queue> #include <algorithm> #include <unordered_map> using namespace std; typedef pair<int, int> Value; constexpr int P = 1696969; namespace std { template<> struct hash<Value> { size_t operator() (const Value& x) const& { auto [a, b] = x; return (a * P) + b; } }; } long long mod = 1000000007; long long f(int start, int finish, vector<long long>& work, vector<long long>& v, unordered_map <Value, int>& M); long long g(int start, int finish, vector <long long> work, vector<long long>& v, unordered_map <Value, int>& M) { //otwarto domkniety if (start == finish) return 1; if (M.find({ start, finish })!=M.end()) return M[{start, finish}]; long long temp = f(start + 1, finish, work, v, M); M[{start, finish}] = temp; return temp; } long long f(int start, int finish, vector<long long> &work, vector<long long>& v, unordered_map <Value, int> &M) { //domknieto domkniety priority_queue<int> Q; work[start] = (v[start]) %mod; if (!(work[start] % 2)) Q.push(start); for (int i = start + 1; i <= finish; i++) { work[i] = (work[i - 1] + v[i]) % mod; if (!(work[i] % 2)) Q.push(i); } if (start == finish && work[finish] % 2 == 1) return 0; long long ans = 0; while (!Q.empty()) { ans += g(Q.top(), finish, work, v, M); ans %= mod; Q.pop(); } return ans; } int main() { cin.tie(0); ios_base::sync_with_stdio(0); int n; cin >> n; unordered_map <Value, int> M; vector <long long> vec(n); for (auto& x : vec) cin >> x; vector <long long> work(n); cout << f(0, n - 1, work, vec, M) << "\n"; }
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 | #include <iostream> #include <vector> #include <queue> #include <algorithm> #include <unordered_map> using namespace std; typedef pair<int, int> Value; constexpr int P = 1696969; namespace std { template<> struct hash<Value> { size_t operator() (const Value& x) const& { auto [a, b] = x; return (a * P) + b; } }; } long long mod = 1000000007; long long f(int start, int finish, vector<long long>& work, vector<long long>& v, unordered_map <Value, int>& M); long long g(int start, int finish, vector <long long> work, vector<long long>& v, unordered_map <Value, int>& M) { //otwarto domkniety if (start == finish) return 1; if (M.find({ start, finish })!=M.end()) return M[{start, finish}]; long long temp = f(start + 1, finish, work, v, M); M[{start, finish}] = temp; return temp; } long long f(int start, int finish, vector<long long> &work, vector<long long>& v, unordered_map <Value, int> &M) { //domknieto domkniety priority_queue<int> Q; work[start] = (v[start]) %mod; if (!(work[start] % 2)) Q.push(start); for (int i = start + 1; i <= finish; i++) { work[i] = (work[i - 1] + v[i]) % mod; if (!(work[i] % 2)) Q.push(i); } if (start == finish && work[finish] % 2 == 1) return 0; long long ans = 0; while (!Q.empty()) { ans += g(Q.top(), finish, work, v, M); ans %= mod; Q.pop(); } return ans; } int main() { cin.tie(0); ios_base::sync_with_stdio(0); int n; cin >> n; unordered_map <Value, int> M; vector <long long> vec(n); for (auto& x : vec) cin >> x; vector <long long> work(n); cout << f(0, n - 1, work, vec, M) << "\n"; } |