結果

問題 No.906 Y字グラフ
コンテスト
ユーザー polylogK
提出日時 2019-10-11 22:05:22
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
WA  
実行時間 -
コード長 4,044 bytes
コンパイル時間 1,485 ms
コンパイル使用メモリ 167,208 KB
実行使用メモリ 6,820 KB
最終ジャッジ日時 2024-11-25 07:32:06
合計ジャッジ時間 2,437 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge3
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ファイルパターン 結果
sample AC * 4
other AC * 21 WA * 7
権限があれば一括ダウンロードができます

ソースコード

diff # 

#include <bits/stdc++.h>
using namespace std::literals::string_literals;
using i64 = std::int_fast64_t;
using std::cout;
using std::endl;
using std::cin;

template<typename T>
std::vector<T> make_v(size_t a){return std::vector<T>(a);}

template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts){
  return std::vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}

template <std::uint_fast64_t Modulus>
class modint {
	using u32 = std::uint_fast32_t;
	using u64 = std::uint_fast64_t;
	using i64 = std::int_fast64_t;
	
	public:
	u64 a;

	constexpr modint() noexcept : a(0) {}
	constexpr modint(const u64 & x) noexcept : a(x % Modulus) {}

	constexpr u64 &value() noexcept { return a; }
	constexpr const u64 &value() const noexcept { return a; }

	const modint inverse() const {
		i64 x = a, b = Modulus, u = 1, v = 0;
		while(b > 0) {
			auto t = x / b;

			std::swap(x -= t * b, b);
			std::swap(u -= t * v, v);
		}
		return modint(u);
	}
	const modint pow(i64 k) const {
		return modint(*this) ^ k;
	}

	static u64 mod() { return Modulus; }

	constexpr modint & operator+=(const modint & rhs) noexcept {
		a += rhs.a;
		if (a >= Modulus) a -= Modulus;
		return *this;
	}
	constexpr modint & operator-=(const modint & rhs) noexcept {
		if (a < rhs.a) a += Modulus;
		a -= rhs.a;
		return *this;
	}
	constexpr modint & operator*=(const modint & rhs) noexcept {
		a = a * rhs.a % Modulus;
		return *this;
	}
	constexpr modint & operator/=(modint rhs) noexcept {
		u64 exp = Modulus - 2;
		while (exp) {
			if (exp % 2) (*this) *= rhs;
			
			rhs *= rhs;
			exp /= 2;
		}
		return *this;
	}
	constexpr modint & operator^=(u64 k) noexcept {
		auto b = modint(1);
		while(k) {
			if(k & 1) b = b * (*this);
			(*this) *= (*this);
			k >>= 1;
		}
		return (*this) = b;
	}
	constexpr modint & operator=(const modint & rhs) noexcept {
		a = rhs.a;
		return (*this);
	}
	constexpr modint operator+(const modint & rhs) const noexcept { return modint(*this) += rhs; }
	constexpr modint operator-(const modint & rhs) const noexcept { return modint(*this) -= rhs; }	
	constexpr modint operator*(const modint & rhs) const noexcept { return modint(*this) *= rhs; }
	constexpr modint operator/(const modint & rhs) const noexcept { return modint(*this) /= rhs; }
	constexpr modint operator^(const u64 & k) const noexcept { return modint(*this) ^= k; }
	constexpr modint operator-() const noexcept { return modint(Modulus - a); }
	constexpr modint operator++() noexcept { return (*this) = modint(*this) + 1; }
	constexpr modint operator--() noexcept { return (*this) = modint(*this) - 1; }
	const bool operator==(const modint & rhs) const noexcept { return a == rhs.a; };
	const bool operator!=(const modint & rhs) const noexcept { return a != rhs.a; };
	const bool operator<=(const modint & rhs) const noexcept { return a <= rhs.a; };
	const bool operator>=(const modint & rhs) const noexcept { return a >= rhs.a; };
	const bool operator<(const modint & rhs) const noexcept { return a < rhs.a; };
	const bool operator>(const modint & rhs) const noexcept { return a > rhs.a; };
	explicit operator bool() const { return a; }
	explicit operator u32() const { return a; }

	friend std::ostream & operator<<(std::ostream & os, const modint & p) {
		return os << p.a;
	}
	friend std::istream & operator>>(std::istream & is, modint & p) {
		u64 t;
		is >> t;
		p = modint(t);
		return is;
	}
};
using mint = modint<(int)(1e9 + 7)>;

int main() {
	i64 n; scanf("%lld", &n);
	if(n <= 5) {
		printf("1\n");
		return 0;
	} else if(n == 6) {
		printf("2\n");
		return 0;
	}
	n -= 4;

	auto calc_even = [&](i64 n) {
		i64 I = n / 6;
		mint A = (mint)(I + 1) * n / 2;
		mint B = (mint)I * (I + 1) * 3 / 2;
		return A - B;
	};
	auto calc_odd = [&](i64 n) {
		i64 I = (n - 1) / 6;
		mint A = (mint)(I + 1) * (n - 1) / 2;
		mint B = (mint)I * (I + 1) * 3 / 2;
		return A - B;
	};
	
	mint ans = (n + 1) / 3LL + 1;
	if(n & 1) {
		ans += calc_odd(n) + calc_even(n - 3);
	} else {
		ans += calc_even(n) + calc_odd(n - 3);
	}
	printf("%lld\n", ans.value());
	return 0;
}
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