結果

問題 No.978 Fibonacci Convolution Easy
ユーザー r1933
提出日時 2020-02-04 16:00:54
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 88 ms / 2,000 ms
コード長 5,492 bytes
コンパイル時間 1,709 ms
コンパイル使用メモリ 169,308 KB
実行使用メモリ 18,812 KB
最終ジャッジ日時 2024-09-21 07:24:17
合計ジャッジ時間 3,249 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge2
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ファイルパターン 結果
other AC * 21
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ソースコード

diff # 

#include "bits/stdc++.h"
#pragma GCC optimize("Ofast")

// Begin Header {{{
using namespace std;

#ifndef DEBUG
#define dump(...)
#endif

#define all(x) x.begin(), x.end()
#define rep(i, n) for (intmax_t i = 0, i##_limit = (n); i < i##_limit; ++i)
#define reps(i, b, e) for (intmax_t i = (b), i##_limit = (e); i <= i##_limit; ++i)
#define repr(i, b, e) for (intmax_t i = (b), i##_limit = (e); i >= i##_limit; --i)
#define var(Type, ...) Type __VA_ARGS__; input(__VA_ARGS__)

constexpr size_t    operator""_zu(unsigned long long value) { return value; };
constexpr intmax_t  operator""_jd(unsigned long long value) { return value; };
constexpr uintmax_t operator""_ju(unsigned long long value) { return value; };

constexpr int INF = 0x3f3f3f3f;
constexpr intmax_t LINF = 0x3f3f3f3f3f3f3f3f_jd;

template <class T>
using MaxHeap = priority_queue<T, vector<T>, less<T>>;
template <class T>
using MinHeap = priority_queue<T, vector<T>, greater<T>>;

inline void input() {}
template <class Head, class... Tail>
inline void input(Head&& head, Tail&&... tail) {
    cin >> head;
    input(forward<Tail>(tail)...);
}

template <class T>
inline void input(vector<T> &vec) {
    for (auto &e: vec) {
        cin >> e;
    }
}

template <class T>
inline void input(vector<vector<T>> &mat) {
    for (auto &vec: mat) {
        input(vec);
    }
}

inline void print() { cout << "\n"; }
template <class Head, class... Tail>
inline void print(Head&& head, Tail&&... tail) {
    cout << head;
    if (sizeof...(tail)) {
        cout << ' ';
    }
    print(forward<Tail>(tail)...);
}

template <class T>
inline ostream& operator<<(ostream &strm, const vector<T> &vec) {
    static constexpr const char *delim[] = {" ", ""};
    for (const auto &e: vec) {
        strm << e << delim[&e == &vec.back()];
    }
    return strm;
}

template <class T>
inline vector<T> make_v(const T &initValue, size_t sz) {
    return vector<T>(sz, initValue);
}

template <class T, class... Args>
inline auto make_v(const T &initValue, size_t sz, Args... args) {
    return vector<decltype(make_v<T>(initValue, args...))>(sz, make_v<T>(initValue, args...));
}

template <class Func>
class FixPoint : Func {
public:
    explicit constexpr FixPoint(Func&& f) noexcept : Func(forward<Func>(f)) {}

    template <class... Args>
    constexpr decltype(auto) operator()(Args&&... args) const {
        return Func::operator()(*this, std::forward<Args>(args)...);
    }
};

template <class Func>
static inline constexpr decltype(auto) makeFixPoint(Func&& f) noexcept {
    return FixPoint<Func>{forward<Func>(f)};
}

template <class T>
inline bool chmax(T &a, const T &b) noexcept {
    return b > a && (a = b, true);
}

template <class T>
inline bool chmin(T &a, const T &b) noexcept {
    return b < a && (a = b, true);
}

template <class T>
inline T diff(const T &a, const T &b) noexcept {
    return a < b ? b - a : a - b;
}
// }}}

constexpr intmax_t MOD = intmax_t(1e9) + 7;

// Mint {{{
template <intmax_t MOD>
class ModInt {
    intmax_t value;

public:
    inline ModInt(const ModInt& other) noexcept : value(other.value) {}
    inline ModInt(intmax_t value = 0) noexcept :
        value((value >= MOD) ? value % MOD : (value < 0) ? (value + MOD) % MOD : value) {}

    inline ModInt inv() const noexcept { return pow(value, MOD - 2); }

    inline ModInt& operator+=(const ModInt& other) noexcept {
        value = (value + other.value) % MOD; return *this;
    }
    inline ModInt& operator-=(const ModInt& other) noexcept {
        value = (MOD + value - other.value) % MOD; return *this;
    }
    inline ModInt& operator*=(const ModInt& other) noexcept {
        value = (value * other.value) % MOD; return *this;
    }
    inline ModInt& operator/=(const ModInt& other) noexcept {
        value = (value * other.inv().value) % MOD; return *this;
    }

    inline ModInt operator+(const ModInt& other) noexcept { return ModInt(*this) += other; }
    inline ModInt operator-(const ModInt& other) noexcept { return ModInt(*this) -= other; }
    inline ModInt operator*(const ModInt& other) noexcept { return ModInt(*this) *= other; }
    inline ModInt operator/(const ModInt& other) noexcept { return ModInt(*this) /= other; }

    inline bool operator==(const ModInt& other) noexcept { return value == *other; }
    inline bool operator!=(const ModInt& other) noexcept { return value != *other; }

    template <class int_>
        explicit inline operator int_() const noexcept { return static_cast<int_>(value); }

    friend ostream& operator<<(ostream &os, ModInt other) noexcept {
        os << other.value; return os;
    }

    friend istream& operator>>(istream &is, ModInt& other) noexcept {
        is >> other.value; return is;
    }

    static constexpr inline ModInt pow(intmax_t n, intmax_t p) noexcept {
        intmax_t ret = 1;
        for (; p > 0; p >>= 1) {
            if (p & 1) ret = (ret * n) % MOD;
            n = (n * n) % MOD;
        }
        return ret;
    }
};

using Mint = ModInt<MOD>;
// }}}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    var(size_t, N);
    var(Mint, p);

    if (N == 1) {
        return print(0), 0;
    } else if (N == 2) {
        return print(1), 0;
    }

    vector<Mint> a(N + 1);
    a[1] = 0;
    a[2] = 1;
    reps(i, 3, N) {
        a[i] = p * a[i - 1] + a[i - 2];
    }

    Mint res = 0, cumSum = 0;
    reps(i, 1, N) {
        cumSum += a[i];
        res += a[i] * cumSum;
    }

    print(res);

    return 0;
}
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