#969703 (C++17) No.2717 Sum of Subarray of Subsequence

• 問題: No.2717 Sum of Subarray of Subsequence
• ユーザー: GOTKAKO
• 提出日時: 2024-04-05 22:01:40
• 言語: C++17 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 60 ms / 2,000 ms
• コード長: 2,446 bytes
• コンパイル時間: 2,209 ms
• コンパイル使用メモリ: 198,476 KB
• 最終ジャッジ日時: 2025-02-20 21:22:08
• ジャッジサーバーID （参考情報）: judge1 / judge2

ファイルパターン	結果
sample	AC * 3
other	AC * 21

ソースコード

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#include <bits/stdc++.h>
using namespace std;
long long mod = 998244353;
//入力が必ずmod未満の時に使う.
struct mint{
    long long v = 0;
    mint(){} mint(int a){v = a;} mint(long long a){v = a;} mint(unsigned long long a){v = a;}
    long long val(){return v;}
    void modu(){v %= mod;}
 
    mint repeat2mint(long long a,long long b){
        mint ret = 1,p = a;
        while(b){if(b&1) ret *= p; p *= p; b >>= 1;}
        return ret;
    };
 
    mint operator-(){return mint(0)-mint(v);}
    mint operator+(mint b){return (v+b.v)%mod;}
    mint operator-(mint b){return (v-b.v+mod)%mod;}
    mint operator*(mint b){return v*b.v%mod;}
    mint operator/(mint b){
        if(b.v == 0) assert(false);
        return v*(repeat2mint(b.v,mod-2)).v%mod;
    }
 
    void operator+=(mint b){v = (v+b.v)%mod;}
    void operator-=(mint b){v = (v-b.v+mod)%mod;}
    void operator*=(mint b){v = v*b.v%mod;}
    void operator/=(mint b){
    if(b.v == 0) assert(false);
        v = v*repeat2mint(b.v,mod-2).v%mod;
    }
 
    void operator++(int){v = (v+1)%mod; return;}
    void operator--(int){v = (v-1+mod)%mod; return;}
    bool operator==(mint b){return v == b.v;}
    bool operator!=(mint b){return v != b.v;}
    bool operator>(mint b) {return v >  b.v;}
    bool operator>=(mint b){return v >= b.v;}
    bool operator<(mint b) {return v <  b.v;}
    bool operator<=(mint b){return v <= b.v;}
 
    mint pow(long long x){return repeat2mint(v,x);}
    mint inv(){return mint(1)/v;}
};          
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int N; cin >> N;
    vector<mint> A(N);
    for(auto &a : A) cin >> a.v;
    int Limit = N;
    vector<mint> fac(Limit+1,1),inv(Limit+1,1),facinv(Limit+1,1);
    for(int i=1; i<=Limit; i++) fac.at(i).v = fac.at(i-1).v*i %mod;
    for(int i=2; i<=Limit; i++) inv.at(i).v = mod-(mod/i*inv.at(mod%i).v %mod);
    for(int i=2; i<=Limit; i++) facinv.at(i).v = facinv.at(i-1).v*inv.at(i).v %mod;
    auto nCr = [&](int n, int r) -> mint {
        //if(n < r) return mint(0);
        return fac.at(n)*facinv.at(r)*facinv.at(n-r);
    };
    vector<mint> p2(N,1);
    for(int i=1; i<N; i++) p2.at(i) = p2.at(i-1)*2;
    vector<mint> NCr(N,1);
    for(int i=1; i<N; i++) NCr.at(i) = p2.at(i)+p2.at(i-1)*i;
    mint answer = 0;
    for(int i=0; i<N; i++){
        int l = i,r = N-1-i;
        answer += NCr.at(l)*NCr.at(r)*A.at(i);
    }
    cout << answer.v << endl;
}
 
 
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