test/convolution/convolution_mod.0.test.cpp

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Last update: 2025-01-19 15:28:01+08:00
Problem: https://judge.yosupo.jp/problem/convolution_mod

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Code

#define PROBLEM "https://judge.yosupo.jp/problem/convolution_mod"

#include "fft.hpp"
#include "modint.hpp"
#include <iostream>
#include <vector>

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    using mint = ModInt<998244353>;
    int n, m;
    std::cin >> n >> m;
    std::vector<mint> a(n), b(m);
    for (int i = 0; i < n; ++i) std::cin >> a[i];
    for (int i = 0; i < m; ++i) std::cin >> b[i];
    const auto ab = convolution(a, b);
    for (int i = 0; i < n + m - 1; ++i) std::cout << ab[i] << ' ';
    return 0;
}

#line 1 "test/convolution/convolution_mod.0.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/convolution_mod"

#line 2 "fft.hpp"

#include <algorithm>
#include <cassert>
#include <iterator>
#include <memory>
#include <vector>

template<typename Tp> class FftInfo {
    static Tp least_quadratic_nonresidue() {
        for (int i = 2;; ++i)
            if (Tp(i).pow((Tp::mod() - 1) / 2) == -1) return Tp(i);
    }

    const int ordlog2_;
    const Tp zeta_;
    const Tp invzeta_;
    const Tp imag_;
    const Tp invimag_;

    mutable std::vector<Tp> root_;
    mutable std::vector<Tp> invroot_;

    FftInfo()
        : ordlog2_(__builtin_ctzll(Tp::mod() - 1)),
          zeta_(least_quadratic_nonresidue().pow((Tp::mod() - 1) >> ordlog2_)),
          invzeta_(zeta_.inv()), imag_(zeta_.pow(1LL << (ordlog2_ - 2))), invimag_(-imag_),
          root_{Tp(1), imag_}, invroot_{Tp(1), invimag_} {}

public:
    static const FftInfo &get() {
        static FftInfo info;
        return info;
    }

    Tp imag() const { return imag_; }
    Tp inv_imag() const { return invimag_; }
    Tp zeta() const { return zeta_; }
    Tp inv_zeta() const { return invzeta_; }
    const std::vector<Tp> &root(int n) const {
        // [0, n)
        assert((n & (n - 1)) == 0);
        if (const int s = root_.size(); s < n) {
            root_.resize(n);
            for (int i = __builtin_ctz(s); (1 << i) < n; ++i) {
                const int j = 1 << i;
                root_[j]    = zeta_.pow(1LL << (ordlog2_ - i - 2));
                for (int k = j + 1; k < j * 2; ++k) root_[k] = root_[k - j] * root_[j];
            }
        }
        return root_;
    }
    const std::vector<Tp> &inv_root(int n) const {
        // [0, n)
        assert((n & (n - 1)) == 0);
        if (const int s = invroot_.size(); s < n) {
            invroot_.resize(n);
            for (int i = __builtin_ctz(s); (1 << i) < n; ++i) {
                const int j = 1 << i;
                invroot_[j] = invzeta_.pow(1LL << (ordlog2_ - i - 2));
                for (int k = j + 1; k < j * 2; ++k) invroot_[k] = invroot_[k - j] * invroot_[j];
            }
        }
        return invroot_;
    }
};

inline int fft_len(int n) {
    --n;
    n |= n >> 1, n |= n >> 2, n |= n >> 4, n |= n >> 8;
    return (n | n >> 16) + 1;
}

namespace detail {

template<typename Iterator> inline void
butterfly_n(Iterator a, int n,
            const std::vector<typename std::iterator_traits<Iterator>::value_type> &root) {
    assert(n > 0);
    assert((n & (n - 1)) == 0);
    const int bn = __builtin_ctz(n);
    if (bn & 1) {
        for (int i = 0; i < n / 2; ++i) {
            const auto a0 = a[i], a1 = a[i + n / 2];
            a[i] = a0 + a1, a[i + n / 2] = a0 - a1;
        }
    }
    for (int i = n >> (bn & 1); i >= 4; i /= 4) {
        const int i4 = i / 4;
        for (int k = 0; k < i4; ++k) {
            const auto a0 = a[k + i4 * 0], a1 = a[k + i4 * 1];
            const auto a2 = a[k + i4 * 2], a3 = a[k + i4 * 3];
            const auto a02p = a0 + a2, a02m = a0 - a2;
            const auto a13p = a1 + a3, a13m = (a1 - a3) * root[1];
            a[k + i4 * 0] = a02p + a13p, a[k + i4 * 1] = a02p - a13p;
            a[k + i4 * 2] = a02m + a13m, a[k + i4 * 3] = a02m - a13m;
        }
        for (int j = i, m = 2; j < n; j += i, m += 2) {
            const auto r = root[m], r2 = r * r, r3 = r2 * r;
            for (int k = j; k < j + i4; ++k) {
                const auto a0 = a[k + i4 * 0], a1 = a[k + i4 * 1] * r;
                const auto a2 = a[k + i4 * 2] * r2, a3 = a[k + i4 * 3] * r3;
                const auto a02p = a0 + a2, a02m = a0 - a2;
                const auto a13p = a1 + a3, a13m = (a1 - a3) * root[1];
                a[k + i4 * 0] = a02p + a13p, a[k + i4 * 1] = a02p - a13p;
                a[k + i4 * 2] = a02m + a13m, a[k + i4 * 3] = a02m - a13m;
            }
        }
    }
}

template<typename Iterator> inline void
inv_butterfly_n(Iterator a, int n,
                const std::vector<typename std::iterator_traits<Iterator>::value_type> &root) {
    assert(n > 0);
    assert((n & (n - 1)) == 0);
    const int bn = __builtin_ctz(n);
    for (int i = 4; i <= (n >> (bn & 1)); i *= 4) {
        const int i4 = i / 4;
        for (int k = 0; k < i4; ++k) {
            const auto a0 = a[k + i4 * 0], a1 = a[k + i4 * 1];
            const auto a2 = a[k + i4 * 2], a3 = a[k + i4 * 3];
            const auto a01p = a0 + a1, a01m = a0 - a1;
            const auto a23p = a2 + a3, a23m = (a2 - a3) * root[1];
            a[k + i4 * 0] = a01p + a23p, a[k + i4 * 1] = a01m + a23m;
            a[k + i4 * 2] = a01p - a23p, a[k + i4 * 3] = a01m - a23m;
        }
        for (int j = i, m = 2; j < n; j += i, m += 2) {
            const auto r = root[m], r2 = r * r, r3 = r2 * r;
            for (int k = j; k < j + i4; ++k) {
                const auto a0 = a[k + i4 * 0], a1 = a[k + i4 * 1];
                const auto a2 = a[k + i4 * 2], a3 = a[k + i4 * 3];
                const auto a01p = a0 + a1, a01m = a0 - a1;
                const auto a23p = a2 + a3, a23m = (a2 - a3) * root[1];
                a[k + i4 * 0] = a01p + a23p, a[k + i4 * 1] = (a01m + a23m) * r;
                a[k + i4 * 2] = (a01p - a23p) * r2, a[k + i4 * 3] = (a01m - a23m) * r3;
            }
        }
    }
    if (bn & 1) {
        for (int i = 0; i < n / 2; ++i) {
            const auto a0 = a[i], a1 = a[i + n / 2];
            a[i] = a0 + a1, a[i + n / 2] = a0 - a1;
        }
    }
}

} // namespace detail

// FFT_n: A(x) |-> bit-reversed order of [A(1), A(zeta_n), ..., A(zeta_n^(n-1))]
template<typename Iterator> inline void fft_n(Iterator a, int n) {
    using Tp = typename std::iterator_traits<Iterator>::value_type;
    detail::butterfly_n(a, n, FftInfo<Tp>::get().root(n / 2));
}

template<typename Tp> inline void fft(std::vector<Tp> &a) { fft_n(a.begin(), a.size()); }

// IFFT_n: bit-reversed order of [A(1), A(zeta_n), ..., A(zeta_n^(n-1))] |-> A(x)
template<typename Iterator> inline void inv_fft_n(Iterator a, int n) {
    using Tp = typename std::iterator_traits<Iterator>::value_type;
    detail::inv_butterfly_n(a, n, FftInfo<Tp>::get().inv_root(n / 2));
    const Tp iv = Tp::mod() - (Tp::mod() - 1) / n;
    for (int i = 0; i < n; ++i) a[i] *= iv;
}

template<typename Tp> inline void inv_fft(std::vector<Tp> &a) { inv_fft_n(a.begin(), a.size()); }

// IFFT_n^T: A(x) |-> 1/n FFT_n((x^n A(x^(-1))) mod (x^n - 1))
template<typename Iterator> inline void transposed_inv_fft_n(Iterator a, int n) {
    using Tp    = typename std::iterator_traits<Iterator>::value_type;
    const Tp iv = Tp::mod() - (Tp::mod() - 1) / n;
    for (int i = 0; i < n; ++i) a[i] *= iv;
    detail::butterfly_n(a, n, FftInfo<Tp>::get().inv_root(n / 2));
}

template<typename Tp> inline void transposed_inv_fft(std::vector<Tp> &a) {
    transposed_inv_fft_n(a.begin(), a.size());
}

// FFT_n^T : FFT_n((x^n A(x^(-1))) mod (x^n - 1)) |-> n A(x)
template<typename Iterator> inline void transposed_fft_n(Iterator a, int n) {
    using Tp = typename std::iterator_traits<Iterator>::value_type;
    detail::inv_butterfly_n(a, n, FftInfo<Tp>::get().root(n / 2));
}

template<typename Tp> inline void transposed_fft(std::vector<Tp> &a) {
    transposed_fft_n(a.begin(), a.size());
}

template<typename Tp> inline std::vector<Tp> convolution_fft(std::vector<Tp> a, std::vector<Tp> b) {
    if (a.empty() || b.empty()) return {};
    const int n   = a.size();
    const int m   = b.size();
    const int len = fft_len(n + m - 1);
    a.resize(len);
    b.resize(len);
    fft(a);
    fft(b);
    for (int i = 0; i < len; ++i) a[i] *= b[i];
    inv_fft(a);
    a.resize(n + m - 1);
    return a;
}

template<typename Tp> inline std::vector<Tp> square_fft(std::vector<Tp> a) {
    if (a.empty()) return {};
    const int n   = a.size();
    const int len = fft_len(n * 2 - 1);
    a.resize(len);
    fft(a);
    for (int i = 0; i < len; ++i) a[i] *= a[i];
    inv_fft(a);
    a.resize(n * 2 - 1);
    return a;
}

template<typename Tp>
inline std::vector<Tp> convolution_naive(const std::vector<Tp> &a, const std::vector<Tp> &b) {
    if (a.empty() || b.empty()) return {};
    const int n = a.size();
    const int m = b.size();
    std::vector<Tp> res(n + m - 1);
    for (int i = 0; i < n; ++i)
        for (int j = 0; j < m; ++j) res[i + j] += a[i] * b[j];
    return res;
}

template<typename Tp>
inline std::vector<Tp> convolution(const std::vector<Tp> &a, const std::vector<Tp> &b) {
    if (std::min(a.size(), b.size()) < 60) return convolution_naive(a, b);
    if (std::addressof(a) == std::addressof(b)) return square_fft(a);
    return convolution_fft(a, b);
}
#line 2 "modint.hpp"

#include <iostream>
#include <type_traits>

// clang-format off
template<unsigned Mod> class ModInt {
    static_assert((Mod >> 31) == 0, "`Mod` must less than 2^(31)");
    template<typename Int>
    static std::enable_if_t<std::is_integral_v<Int>, unsigned> safe_mod(Int v) { using D = std::common_type_t<Int, unsigned>; return (v %= (int)Mod) < 0 ? (D)(v + (int)Mod) : (D)v; }
    struct PrivateConstructor {} static inline private_constructor{};
    ModInt(PrivateConstructor, unsigned v) : v_(v) {}
    unsigned v_;

public:
    static unsigned mod() { return Mod; }
    static ModInt from_raw(unsigned v) { return ModInt(private_constructor, v); }
    static ModInt zero() { return from_raw(0); }
    static ModInt one() { return from_raw(1); }
    bool is_zero() const { return v_ == 0; }
    bool is_one() const { return v_ == 1; }
    ModInt() : v_() {}
    template<typename Int, typename std::enable_if_t<std::is_signed_v<Int>, int> = 0> ModInt(Int v) : v_(safe_mod(v)) {}
    template<typename Int, typename std::enable_if_t<std::is_unsigned_v<Int>, int> = 0> ModInt(Int v) : v_(v % Mod) {}
    unsigned val() const { return v_; }
    ModInt operator-() const { return from_raw(v_ == 0 ? v_ : Mod - v_); }
    ModInt pow(long long e) const { if (e < 0) return inv().pow(-e); for (ModInt x(*this), res(from_raw(1));; x *= x) { if (e & 1) res *= x; if ((e >>= 1) == 0) return res; }}
    ModInt inv() const { int x1 = 1, x3 = 0, a = val(), b = Mod; while (b) { const int q = a / b, x1_old = x1, a_old = a; x1 = x3, x3 = x1_old - x3 * q, a = b, b = a_old - b * q; } return from_raw(x1 < 0 ? x1 + (int)Mod : x1); }
    template<bool Odd = (Mod & 1)> std::enable_if_t<Odd, ModInt> div_by_2() const { if (v_ & 1) return from_raw((v_ + Mod) >> 1); return from_raw(v_ >> 1); }
    ModInt &operator+=(const ModInt &a) { if ((v_ += a.v_) >= Mod) v_ -= Mod; return *this; }
    ModInt &operator-=(const ModInt &a) { if ((v_ += Mod - a.v_) >= Mod) v_ -= Mod; return *this; }
    ModInt &operator*=(const ModInt &a) { v_ = (unsigned long long)v_ * a.v_ % Mod; return *this; }
    ModInt &operator/=(const ModInt &a) { return *this *= a.inv(); }
    ModInt &operator++() { return *this += one(); }
    ModInt operator++(int) { ModInt o(*this); *this += one(); return o; }
    ModInt &operator--() { return *this -= one(); }
    ModInt operator--(int) { ModInt o(*this); *this -= one(); return o; }
    friend ModInt operator+(const ModInt &a, const ModInt &b) { return ModInt(a) += b; }
    friend ModInt operator-(const ModInt &a, const ModInt &b) { return ModInt(a) -= b; }
    friend ModInt operator*(const ModInt &a, const ModInt &b) { return ModInt(a) *= b; }
    friend ModInt operator/(const ModInt &a, const ModInt &b) { return ModInt(a) /= b; }
    friend bool operator==(const ModInt &a, const ModInt &b) { return a.v_ == b.v_; }
    friend bool operator!=(const ModInt &a, const ModInt &b) { return a.v_ != b.v_; }
    friend std::istream &operator>>(std::istream &a, ModInt &b) { int v; a >> v; b.v_ = safe_mod(v); return a; }
    friend std::ostream &operator<<(std::ostream &a, const ModInt &b) { return a << b.val(); }
};
// clang-format on
#line 7 "test/convolution/convolution_mod.0.test.cpp"

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    using mint = ModInt<998244353>;
    int n, m;
    std::cin >> n >> m;
    std::vector<mint> a(n), b(m);
    for (int i = 0; i < n; ++i) std::cin >> a[i];
    for (int i = 0; i < m; ++i) std::cin >> b[i];
    const auto ab = convolution(a, b);
    for (int i = 0; i < n + m - 1; ++i) std::cout << ab[i] << ' ';
    return 0;
}