結果

問題 No.2717 Sum of Subarray of Subsequence
コンテスト
ユーザー ゆにぽけ
提出日時 2024-04-05 22:24:50
言語 C++17
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 47 ms / 2,000 ms
コード長 4,108 bytes
コンパイル時間 1,439 ms
コンパイル使用メモリ 127,596 KB
最終ジャッジ日時 2025-02-20 21:40:09
ジャッジサーバーID
（参考情報） 		judge1 / judge2
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 21
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ソースコード

diff # 

#include <iostream>
#include <vector>
#include <algorithm>
#include <array>
#include <iterator>
#include <string>
#include <cctype>
#include <cstring>
#include <cstdlib>
#include <cassert>
#include <cmath>
#include <ctime>
#include <iomanip>
#include <numeric>
#include <stack>
#include <queue>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <bitset>
#include <random>
#include <utility>
#include <functional>
using namespace std;
template<int m> struct modint
{
	private:
	unsigned int value;
	static constexpr int mod() {return m;}

	public:
	constexpr modint(const long long x = 0) noexcept
	{
		long long y = x;
		if(y < 0 || y >= mod())
		{
			y %= mod();
			if(y < 0) y += mod();
		}
		value = (unsigned int)y;
	}
	static constexpr int get_mod() noexcept {return m;}
	static constexpr int primitive_root() noexcept
	{
		assert(m == 998244353);
		return 3;
	}
	constexpr unsigned int val() noexcept {return value;}
	constexpr modint &operator+=(const modint &other) noexcept
	{
		value += other.value;
		if(value >= mod()) value -= mod();
		return *this;
	}
	constexpr modint &operator-=(const modint &other) noexcept
	{
		unsigned int x = value;
		if(x < other.value) x += mod();
		x -= other.value;
		value = x;
		return *this;
	}
	constexpr modint &operator*=(const modint &other) noexcept
	{
		unsigned long long x = value;
		x *= other.value;
		value = (unsigned int) (x % mod());
		return *this;
	}
	constexpr modint &operator/=(const modint &other) noexcept
	{
		return *this *= other.inverse();
	}
	constexpr modint inverse() const noexcept
	{
		assert(value);
		long long a = value,b = mod(),x = 1,y = 0;
		while(b)
		{
			long long q = a/b;
			a -= q*b; swap(a,b);
			x -= q*y; swap(x,y);
		}
		return modint(x);
	}
	constexpr modint power(long long N) const noexcept
	{
		assert(N >= 0);
		modint p = *this,ret = 1;
		while(N)
		{
			if(N & 1) ret *= p;
			p *= p;
			N >>= 1;
		}
		return ret;
	}
	constexpr modint operator+() {return *this;}
	constexpr modint operator-() {return modint() - *this;}
	constexpr modint &operator++(int) noexcept {return *this += 1;}
	constexpr modint &operator--(int) noexcept {return *this -= 1;}
	friend modint operator+(const modint& lhs, const modint& rhs) {return modint(lhs) += rhs;}
	friend modint operator-(const modint& lhs, const modint& rhs) {return modint(lhs) -= rhs;}
	friend modint operator*(const modint& lhs, const modint& rhs) {return modint(lhs) *= rhs;}
	friend modint operator/(const modint& lhs, const modint& rhs) {return modint(lhs) /= rhs;}
	friend ostream &operator<<(ostream &os,const modint &x) {return os << x.value;}
};
using mint = modint<998244353>;
/* using mint = modint<1000000007>; */


template<class S>
struct combination
{
	private:
	vector<S> f,invf;

	public:
	combination(int N = 0) : f(1,1),invf(1,1)
	{
		update(N);
	}

	void update(int N)
	{
		if((int)f.size() > N) return;
		int pi = (int)f.size();
		N = max(N,pi*2);

		f.resize(N+1),invf.resize(N+1);

		for(int i = pi;i <= N;i++) f[i] = f[i-1]*i;
		invf[N] = S(1)/f[N];
		for(int i = N-1;i >= pi;i--) invf[i] = invf[i+1]*(i+1);
	}

	S factorial(int N)
	{
		update(N);
		return f[N];
	}

	S invfactorial(int N)
	{
		update(N);
		return invf[N];
	}

	S P(int N,int K)
	{
		assert(0 <= K && K <= N);
		update(N);
		return f[N]*invf[N-K];
	}

	S C(int N,int K)
	{
		assert(0 <= K && K <= N);
		update(N);
		return f[N]*invf[K]*invf[N-K];
	}
};
combination<mint> C;

void Main()
{
	//[l = 0 -> i,r = 0 -> N - i - 1](r + 1) * (l + 1)
	int N;
	cin >> N;
	mint ans = 0;
	vector<mint> t(N + 1);
	t[0] = 1;
	for(int i = 1;i <= N;i++)
	{
		t[i] = t[i - 1] * 2;
	}
	for(int i = 0;i < N;i++)
	{
		int a;
		cin >> a;
		mint cnt = 0;
		mint L = t[i];
		if(i > 0)
		{
			L += i * t[i - 1];
		}
		mint R = t[N - i - 1];
		if(i + 1 < N)
		{
			R += (N - i - 1) * t[N - i - 2];
		}
		cnt += L * R;
		//C(i,l) = 2^i
		//C(i,l) * l = i ! / (l - 1) ! (i - l) ! = i * C(i - 1,l)
		ans += a * cnt;
	}
	cout << ans << "\n";
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int tt = 1;
	/* cin >> tt; */
	while(tt--) Main();
}
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