sotanishy's code snippets for competitive programming
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#define PROBLEM "https://judge.yosupo.jp/problem/find_linear_recurrence" #include "../../math/modint.hpp" #include "../../math/berlekamp_massey.cpp" #include <bits/stdc++.h> using namespace std; using mint = Modint<998244353>; int main() { ios_base::sync_with_stdio(false); cin.tie(nullptr); int N; cin >> N; vector<mint> a(N); for (auto& x : a) cin >> x; auto ans = berlekamp_massey(a); cout << ans.size() << endl; for (int i = 0; i < ans.size(); ++i) { cout << ans[i]; if (i < (int) ans.size() - 1) cout << " "; } cout << endl; }
#line 1 "test/yosupo/find_linear_recurrence.test.cpp" #define PROBLEM "https://judge.yosupo.jp/problem/find_linear_recurrence" #line 2 "math/modint.hpp" #include <algorithm> #include <iostream> /** * @brief Mod int */ template <int m> class Modint { using mint = Modint; static_assert(m > 0, "Modulus must be positive"); public: static constexpr int mod() { return m; } constexpr Modint(long long y = 0) : x(y >= 0 ? y % m : (y % m + m) % m) {} constexpr int val() const { return x; } constexpr mint& operator+=(const mint& r) { if ((x += r.x) >= m) x -= m; return *this; } constexpr mint& operator-=(const mint& r) { if ((x += m - r.x) >= m) x -= m; return *this; } constexpr mint& operator*=(const mint& r) { x = static_cast<int>(1LL * x * r.x % m); return *this; } constexpr mint& operator/=(const mint& r) { return *this *= r.inv(); } constexpr bool operator==(const mint& r) const { return x == r.x; } constexpr mint operator+() const { return *this; } constexpr mint operator-() const { return mint(-x); } constexpr friend mint operator+(const mint& l, const mint& r) { return mint(l) += r; } constexpr friend mint operator-(const mint& l, const mint& r) { return mint(l) -= r; } constexpr friend mint operator*(const mint& l, const mint& r) { return mint(l) *= r; } constexpr friend mint operator/(const mint& l, const mint& r) { return mint(l) /= r; } constexpr mint inv() const { int a = x, b = m, u = 1, v = 0; while (b > 0) { int t = a / b; std::swap(a -= t * b, b); std::swap(u -= t * v, v); } return mint(u); } constexpr mint pow(long long n) const { mint ret(1), mul(x); while (n > 0) { if (n & 1) ret *= mul; mul *= mul; n >>= 1; } return ret; } friend std::ostream& operator<<(std::ostream& os, const mint& r) { return os << r.x; } friend std::istream& operator>>(std::istream& is, mint& r) { long long t; is >> t; r = mint(t); return is; } private: int x; }; #line 2 "math/berlekamp_massey.cpp" #include <vector> template <typename T> std::vector<T> berlekamp_massey(const std::vector<T>& a) { int n = a.size(); std::vector<T> B = {1}, C = {1}; T b = 1; int L = 0, m = 1; for (int i = 0; i < n; ++i) { T d = a[i]; for (int j = 1; j < (int) C.size(); ++j) { d += a[i-j] * C[j]; } if (d == 0) { ++m; } else { auto tmp = C; if (C.size() < m + B.size()) { C.resize(m + B.size()); } T f = d / b; for (int j = 0; j < (int) B.size(); ++j) { C[m + j] -= f * B[j]; } if (2 * L <= i) { L = i + 1 - L; b = d; B = tmp; m = 1; } else { ++m; } } } std::vector<T> ret(L); for (int i = 1; i <= L; ++i) { ret[i-1] = -C[i]; } return ret; } #line 5 "test/yosupo/find_linear_recurrence.test.cpp" #include <bits/stdc++.h> using namespace std; using mint = Modint<998244353>; int main() { ios_base::sync_with_stdio(false); cin.tie(nullptr); int N; cin >> N; vector<mint> a(N); for (auto& x : a) cin >> x; auto ans = berlekamp_massey(a); cout << ans.size() << endl; for (int i = 0; i < ans.size(); ++i) { cout << ans[i]; if (i < (int) ans.size() - 1) cout << " "; } cout << endl; }