test/AOJ/DPL_5_A.test.cpp

#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=DPL_5_A&lang=ja"

#include <iostream>
#include <type_traits>

#include "../../Math/Modulo/mod-int.hpp"
#include "../../Algorithm/doubling-pow.hpp"
#include "../../Util/IO/println.hpp"

int main() {
    using Mint = ModInt1000000007;

    int n;
    std::cin >> n;

    Mint k;
    std::cin >> k;

    const auto ans1 = k.pow(n);
    const auto ans2 = doublingPow(k, n);

    static_assert(std::is_same_v<decltype(ans1), decltype(ans2)>);
    assert(ans1 == ans2);


    println(ans1);

    return 0;
}

#line 1 "test/AOJ/DPL_5_A.test.cpp"
#define PROBLEM "http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=DPL_5_A&lang=ja"

#include <iostream>
#include <type_traits>

#line 2 "Math/Modulo/mod-int.hpp"
#include <cstdint>
#include <cassert>
#line 5 "Math/Modulo/mod-int.hpp"
#include <limits>

/**
 * @brief Mod-Int (コンパイル時mod型と実行時mod型)
 */
namespace internal {

template <class ModHolder>
class ModInt {
private:
    int64_t value;

public:
    constexpr ModInt() noexcept
        : value(0) {}

    constexpr ModInt(int64_t v) noexcept
        : value(ModInt::normalized(v)) {}

    static constexpr const ModInt raw(int64_t v) noexcept {
        ModInt ret;
        ret.value = v;
        return ret;
    }

    static constexpr ModInt nullopt() noexcept { return ModInt::raw(std::numeric_limits<int64_t>::min()); }

    constexpr bool isNull() const noexcept { return *this == ModInt::nullopt(); }

    static constexpr int64_t mod() { return ModHolder::mod; }

    static int64_t setMod(int64_t m) noexcept {
        assert(m >= 1);
        return ModHolder::mod = m;
    }

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

    constexpr int64_t val() const noexcept { return value; }

    constexpr ModInt& operator+=(const ModInt& rhs) noexcept {
        if ((value += rhs.value) >= mod()) value -= mod();
        return *this;
    }
    constexpr ModInt& operator-=(const ModInt& rhs) noexcept {
        if ((value -= rhs.value) < 0) value += mod();
        return *this;
    }
    constexpr ModInt& operator*=(const ModInt& rhs) noexcept {
        (value *= rhs.value) %= mod();
        return *this;
    }
    constexpr ModInt& operator/=(const ModInt& rhs) noexcept { return *this *= rhs.inv(); }
    constexpr const ModInt inv() const noexcept { return ModInt(ModInt::inverse(value, mod())); }
    constexpr const ModInt operator+() const noexcept { return *this; }
    constexpr const ModInt operator-() const noexcept { return ModInt(-value); }

    constexpr const ModInt pow(int64_t expv) const noexcept {
        int64_t ret = 1, square = value;
        for (uint64_t p = std::abs(expv); p; p >>= 1) {
            if (p & 1) (ret *= square) %= mod();
            (square *= square) %= mod();
        }
        return (expv < 0) ? (ModInt::raw(1) / ModInt::raw(ret)) : ModInt::raw(ret);
    }

    friend constexpr bool operator==(const ModInt& lhs, const ModInt& rhs) noexcept { return lhs.value == rhs.value; }
    friend constexpr bool operator!=(const ModInt& lhs, const ModInt& rhs) noexcept { return lhs.value != rhs.value; }
    friend constexpr const ModInt operator+(const ModInt& lhs, const ModInt& rhs) noexcept { return ModInt(lhs) += rhs; }
    friend constexpr const ModInt operator-(const ModInt& lhs, const ModInt& rhs) noexcept { return ModInt(lhs) -= rhs; }
    friend constexpr const ModInt operator*(const ModInt& lhs, const ModInt& rhs) noexcept { return ModInt(lhs) *= rhs; }
    friend constexpr const ModInt operator/(const ModInt& lhs, const ModInt& rhs) noexcept { return ModInt(lhs) /= rhs; }

    friend std::ostream& operator<<(std::ostream& os, const ModInt& x) {
#ifdef LOCAL_DEBUG
        if (x.isNull()) return os << "{nullopt}";
#endif
        return os << x.value;
    }

    friend std::istream& operator>>(std::istream& is, ModInt& x) {
        is >> x.value;
        x.value = ModInt::normalized(x.value);
        return is;
    }

private:
    static constexpr int64_t normalized(int64_t n) {
        n = (-mod() <= n && n < mod() ? n : n % mod());
        if (n < 0) n += mod();
        return n;
    }

    static constexpr int64_t inverse(int64_t a, int64_t m) {
        int64_t u = 0, v = 1;
        while (a != 0) {
            const auto t = m / a;
            static_cast<void>(m -= t * a), std::swap(m, a);
            static_cast<void>(u -= t * v), std::swap(u, v);
        }
        assert(m == 1);
        return u;
    }
};

template <int64_t Mod>
struct StaticModHolder {
    static constexpr int64_t mod = Mod;
};

template <int ID>
struct DynamicModHolder {
    static int64_t mod;
};
template <int ID>
int64_t DynamicModHolder<ID>::mod;

}  // namespace internal

template <int64_t Mod>
using StaticModInt = internal::ModInt<internal::StaticModHolder<Mod>>;

using ModInt1000000007 = StaticModInt<int(1e9) + 7>;
using ModInt998244353 = StaticModInt<998244353>;

template <int ID>
using DynamicModInt = internal::ModInt<internal::DynamicModHolder<ID>>;
#line 2 "Algorithm/doubling-pow.hpp"
#include <cmath>
#line 3 "Util/int-alias.hpp"

/**
 * @brief int-alias (整数型のエイリアス)
 */
using i64 = int64_t;
using u64 = uint64_t;
#line 4 "Algorithm/doubling-pow.hpp"

/**
 * @brief doubling-pow() (繰り返し二乗法)
 */
template <class Integer>
constexpr Integer doublingPow(const Integer& n, const i64 expv) {
    Integer ret = 1, square = n;
    for (u64 p = std::abs(expv); p; p >>= 1) {
        if (p & 1) ret *= square;
        square *= square;
    }
    return (expv < 0) ? (1 / ret) : ret;
}
#line 3 "Util/IO/println.hpp"
#include <utility>

/**
 * @brief println() (可変個の値を空白区切りで出力して改行する)
 */
inline void println() {
    std::cout << '\n';
}
template <class Head, class... Tail>
inline void println(Head&& head, Tail&&... tail) {
    std::cout << head << &" "[!sizeof...(tail)];
    println(std::forward<Tail>(tail)...);
}
#line 9 "test/AOJ/DPL_5_A.test.cpp"

int main() {
    using Mint = ModInt1000000007;

    int n;
    std::cin >> n;

    Mint k;
    std::cin >> k;

    const auto ans1 = k.pow(n);
    const auto ans2 = doublingPow(k, n);

    static_assert(std::is_same_v<decltype(ans1), decltype(ans2)>);
    assert(ans1 == ans2);


    println(ans1);

    return 0;
}