fps/FPS_exp.hpp

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Last update: 2024-09-05 20:11:34+09:00
Include: #include "fps/FPS_exp.hpp"

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Code

#pragma once
#include <vector>
#include <atcoder/convolution>
#include "../fps/FPS_cyclic_convolution.hpp"
#include "../fps/FPS_differetial.hpp"
#include "../fps/FPS_integral.hpp"
#include "FPS_inv.hpp"

namespace po167{
template<class T>
std::vector<T> FPS_exp(std::vector<T> f, int len = -1){
    if (len == -1) len = f.size();
    if (len == 0) return {};
    if (len == 1) return {T(1)};
    assert(!f.empty() && f[0] == 0);
    int s = 1;
    // simple
    std::vector<T> g = {T(1)};
    while (s < len){
        // g' / g
        // A * B
        std::vector<T> A = g, B = g;
        A = FPS_differential(A);
        B = FPS_inv(B, 2 * s);
        A.resize(2 * s);
        A = FPS_cyclic_convolution(A, B);
        A.pop_back();
        A = FPS_integral(A);
        for (int i = 0; i < s; i++) A[i] = 0;
        for (int i = s; i < s * 2; i++) A[i] = (i < (int)f.size() ? f[i] : 0) - A[i];
        // g_hat = g (1 - g + f)
        // g += B = g * A
        g.resize(2 * s);
        B = FPS_cyclic_convolution(A, g);
        for (int i = s; i < s * 2; i++) g[i] = B[i];
        s *= 2;
    }
    g.resize(len);
    return g;
}
}

#line 2 "fps/FPS_exp.hpp"
#include <vector>
#include <atcoder/convolution>
#line 4 "fps/FPS_cyclic_convolution.hpp"

namespace po167{
// |f| = |g| = 2 ^ n
template<class T>
std::vector<T> FPS_cyclic_convolution(std::vector<T> f, std::vector<T> g){
    atcoder::internal::butterfly(f);
    atcoder::internal::butterfly(g);
    for (int i = 0; i < (int)f.size(); i++) f[i] *= g[i];
    atcoder::internal::butterfly_inv(f);
    T iz = (T)(1) / (T)(f.size());
    for (int i = 0; i < (int)f.size(); i++) f[i] *= iz;
    return f;
}
}
#line 3 "fps/FPS_differetial.hpp"

namespace po167{
// return f'
template <class T>
std::vector<T> FPS_differential(std::vector<T> f){
    if (f.empty()) return f;
    for (int i = 0; i < (int)f.size() - 1; i++){
        f[i] = f[i + 1] * (T)(i + 1);
    }
    f.pop_back();
    return f;
}
}
#line 3 "fps/FPS_integral.hpp"

namespace po167{
template <class T>
std::vector<T> FPS_integral(std::vector<T> f){
    if (f.empty()) return f;
    std::vector<T> num_inv((int)f.size() + 1);
    num_inv[0] = 1;
    num_inv[1] = 1;
    auto m = T::mod();
    for (int i = 2; i <= (int)f.size(); i++){
        num_inv[i] = (0 - num_inv[m % i]) * (T)(m / i);
    }
    f.reserve((int)f.size() + 1);
    f.push_back(0);
    for (int i = (int)f.size() - 1; i > 0; i--){
        f[i] = f[i - 1] * num_inv[i];
    }
    f[0] = 0;
    return f;
}
}
#line 4 "fps/FPS_inv.hpp"

namespace po167{
// return 1 / f
template <class T>
std::vector<T> FPS_inv(std::vector<T> f, int len = -1){
    if (len == -1) len = f.size();
    assert(f[0] != 0);
    std::vector<T> g = {1 / f[0]};
    int s = 1;
    while(s < len){
        // g = 2g_s - f(g_s)^2 (mod x ^ (2 * s))
        // g = g - (fg - 1)g
        // (fg - 1) = 0 (mod x ^ (s))
        std::vector<T> n_g(s * 2, 0);
        std::vector<T> f_s(s * 2, 0);
        g.resize(s * 2);
        for (int i = 0; i < s * 2; i++){
            if (int(f.size()) > i) f_s[i] = f[i];
            n_g[i] = g[i];
        }
        atcoder::internal::butterfly(g);
        atcoder::internal::butterfly(f_s);
        for (int i = 0; i < s * 2; i++){
            f_s[i] *= g[i];
        }
        atcoder::internal::butterfly_inv(f_s);
        T iz = 1 / (T)(s * 2);
        for (int i = s; i < s * 2; i++){
            f_s[i] *= iz;
        }
        for (int i = 0; i < s; i++){
            f_s[i] = 0;
        }
        atcoder::internal::butterfly(f_s);
        for (int i = 0; i < s * 2; i++){
            f_s[i] *= g[i];
        }
        atcoder::internal::butterfly_inv(f_s);
        for (int i = s; i < s * 2; i++){
            n_g[i] -= f_s[i] * iz;
        }
        std::swap(n_g, g);
        s *= 2;
    }
    g.resize(len);
    return g;
}
}
#line 8 "fps/FPS_exp.hpp"

namespace po167{
template<class T>
std::vector<T> FPS_exp(std::vector<T> f, int len = -1){
    if (len == -1) len = f.size();
    if (len == 0) return {};
    if (len == 1) return {T(1)};
    assert(!f.empty() && f[0] == 0);
    int s = 1;
    // simple
    std::vector<T> g = {T(1)};
    while (s < len){
        // g' / g
        // A * B
        std::vector<T> A = g, B = g;
        A = FPS_differential(A);
        B = FPS_inv(B, 2 * s);
        A.resize(2 * s);
        A = FPS_cyclic_convolution(A, B);
        A.pop_back();
        A = FPS_integral(A);
        for (int i = 0; i < s; i++) A[i] = 0;
        for (int i = s; i < s * 2; i++) A[i] = (i < (int)f.size() ? f[i] : 0) - A[i];
        // g_hat = g (1 - g + f)
        // g += B = g * A
        g.resize(2 * s);
        B = FPS_cyclic_convolution(A, g);
        for (int i = s; i < s * 2; i++) g[i] = B[i];
        s *= 2;
    }
    g.resize(len);
    return g;
}
}