結果

問題 No.1300 Sum of Inversions
ユーザー hedwig100hedwig100
提出日時 2020-11-27 22:47:31
言語 C++14
(gcc 13.3.0 + boost 1.87.0)
結果
AC  
実行時間 342 ms / 2,000 ms
コード長 5,507 bytes
コンパイル時間 2,108 ms
コンパイル使用メモリ 190,180 KB
実行使用メモリ 39,216 KB
最終ジャッジ日時 2024-07-26 19:07:15
合計ジャッジ時間 10,901 ms
ジャッジサーバーID
（参考情報） 		judge4 / 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 * 34
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;
#ifdef LOCAL_
void debug_out() {cerr << endl;}
template<typename Head,typename... Tail> void debug_out(Head H,Tail... T){cerr << ' ' << H; debug_out(T...);}
#define debug(...) cerr << 'L' << __LINE__ << " [" << #__VA_ARGS__ << "]:",debug_out(__VA_ARGS__)
#define dump(x) cerr << 'L' << __LINE__ << " " << #x << " = " << (x) << endl;
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif
#define rep(i,n) for (int i = 0; i < (int)(n); i ++)
#define irep(i,n) for (int i = (int)(n) - 1;i >= 0;--i)
using ll = long long;
using PL = pair<ll,ll>;
using P = pair<int,int>;
constexpr int INF = 1000000000;
constexpr long long HINF = 100000'00000'00000;
constexpr long long MOD = 998244353;
constexpr double EPS = 1e-4;
constexpr double PI = 3.14159265358979;

#pragma region Macros
template<typename T1,typename T2> ostream &operator<<(ostream &os,const pair<T1,T2> &p) {
    os << '(' << p.first << ',' << p.second << ')'; return os;
}
template<typename T> ostream &operator<<(ostream &os,const vector<T> &v) {
    os << '[';
    for (auto &e:v) {os << e << ',';}
    os << ']'; return os;
}
// grid searh
const int dy[8] = {-1,0,1,0,-1,-1,1,1};
const int dx[8] = {0,1,0,-1,-1,1,-1,1};
bool IN(int y,int x,int H,int W) {return (0 <= y)&&(y < H)&&(0 <= x)&&(x < W);}
#pragma endregion


template<class T> 
struct BinaryIndexedTree {
    int N,power = 1;
    vector<T> bit;

    BinaryIndexedTree(int N = 0): N(N){
        bit.assign(N + 1,0);
        while (power <= N) power <<= 1; //power > N
    }
    void build(const vector<T> &A) {
        for (int i = 1;i <= N; ++i) add(i,A[i - 1]);
    }
    // add x to a[i]
    void add(int i,T x) {
        for (int idx = i; idx <= N; idx += (idx & -idx)) {
            bit[idx] += x;
        }
    }
    // return a[1] + a[2] + a[3] + .. + a[k]
    T sum(int k) {
        T ret = 0;
        for (int idx = k; idx > 0; idx -= (idx & -idx)) {
            ret += bit[idx];
        }
        return ret;
    }
    // return a[l] + a[l + 1] + a[l + 2] + .. + a[r - 1]
    T sum(int l,int r) {
        return sum(r - 1) - sum(l - 1);
    }
    // return min index s.t. a[1] + a[2] + a[3] + .. + a[x] >= w
    int lower_bound(T w) {
        if (w <= 0) return 0;
        int x = 0;
        for (int r = power; r > 0; r >>= 1) {
            if (x + r <= N && bit[x + r] < w) {
                w -= bit[x + r];
                x += r;
            }
        } 
        return x + 1;
    }
};


template<int Modulus> 
struct ModInt {
    long long x;
    ModInt(long long x = 0) :x((x%Modulus + Modulus)%Modulus) {}
    constexpr ModInt &operator+=(const ModInt a) {if ((x += a.x) >= Modulus) x -= Modulus; return *this;}
    constexpr ModInt &operator-=(const ModInt a) {if ((x += Modulus - a.x) >= Modulus) x -= Modulus; return *this;}
    constexpr ModInt &operator*=(const ModInt a) {(x *= a.x) %= Modulus; return *this;}
    constexpr ModInt &operator/=(const ModInt a) {return *this *= a.inverse();}

    constexpr ModInt operator+(const ModInt a) const {return ModInt(*this) += a.x;}
    constexpr ModInt operator-(const ModInt a) const {return ModInt(*this) -= a.x;}
    constexpr ModInt operator*(const ModInt a) const {return ModInt(*this) *= a.x;}
    constexpr ModInt operator/(const ModInt a) const {return ModInt(*this) /= a.x;}
    
    friend constexpr ostream& operator<<(ostream& os,const ModInt<Modulus>& a) {return os << a.x;}
    friend constexpr istream& operator>>(istream& is,ModInt<Modulus>& a) {return is >> a.x;}
    
    ModInt inverse() const {// x ^ (-1) 
        long long a = x,b = Modulus,p = 1,q = 0;
        while (b) {long long d = a/b; a -= d*b; swap(a,b); p -= d*q; swap(p,q);}
        return ModInt(p);
    }
    ModInt pow(long long N) {// x ^ N 
        ModInt a = 1;
        while (N) {
            if (N&1) a *= *this;
            *this *= *this;
            N >>= 1;
        }
        return a;
    }
};

using mint = ModInt<998244353>;

map<ll,int> compress(vector<ll> A) {
    sort(A.begin(),A.end());
    A.erase(unique(A.begin(),A.end()),A.end());
    map<ll,int> mp;
    rep(i,A.size()) mp[A[i]] = i;
    return mp;
}

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);

    int N; cin >> N;
    vector<ll> A(N);
    rep(i,N) cin >> A[i];
    auto mp = compress(A);
    int M = mp.size();
    vector<vector<int>> B(M);
    rep(i,N) {
        int idx = mp[A[i]];
        B[idx].push_back(i);
    }

    vector<ll> cntL(N),cntR(N);
    vector<mint> left(N),right(N);
    mint tot = 0;
    int bf = 0;
    BinaryIndexedTree<mint> bit(N);
    BinaryIndexedTree<int> idx(N);
    rep(i,M) {
        for (int j:B[i]) {
            left[j] = tot - bit.sum(j+1);
            cntL[j] = bf - idx.sum(j+1);
        }
        for (int j:B[i]) {
            bit.add(j+1,mint(A[j]));
            idx.add(j+1,1);
            tot += A[j];
            ++bf;
        }
    }

    BinaryIndexedTree<mint> bit2(N);
    BinaryIndexedTree<int> idx2(N);
    irep(i,M) {
        for (int j:B[i]) {
            right[j] = bit2.sum(j+1);
            cntR[j] = idx2.sum(j+1);
        }
        for (int j:B[i]) {
            bit2.add(j+1,mint(A[j]));
            idx2.add(j+1,1);
        }
    }

    mint ans = 0;
    rep(i,N) {
        ans += cntL[i]*cntR[i]%MOD*A[i];
        if (cntL[i] > 0 && cntR[i] > 0) {
            ans += right[i]*cntL[i];
            ans += left[i]*cntR[i];
        }
    }
    cout << ans << '\n';
    return 0;
}
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