#708144 (C++14) No.1300 Sum of Inversions

• 問題: No.1300 Sum of Inversions
• ユーザー: Aoxiang Cui
• 提出日時: 2021-10-19 00:04:53
• 言語: C++14 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 136 ms / 2,000 ms
• コード長: 7,011 bytes
• コンパイル時間: 1,368 ms
• コンパイル使用メモリ: 125,064 KB
• 実行使用メモリ: 11,068 KB
• 最終ジャッジ日時: 2024-09-19 20:53:11
• 合計ジャッジ時間: 5,990 ms
• ジャッジサーバーID （参考情報）: judge5 / judge3

ファイルパターン	結果
sample	AC * 3
other	AC * 34

コンパイルメッセージ

main.cpp: In function 'int main()':
main.cpp:210:8: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17' [-Wc++17-extensions]
  210 |   auto [L0, L1] = solve(a, 1);
      |        ^
main.cpp:213:8: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17' [-Wc++17-extensions]
  213 |   auto [R0, R1] = solve(a, 0);
      |        ^

ソースコード

#define LOCAL
#define _USE_MATH_DEFINES
#include <array>
#include <cassert>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <iomanip>
#include <string>
#include <sstream>
#include <vector>
#include <queue>
#include <stack>
#include <list>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <algorithm>
#include <complex>
#include <cmath>
#include <numeric>
#include <bitset>
#include <functional>
#include <random>
#include <ctime>

using namespace std;

template <typename A, typename B>
ostream& operator <<(ostream& out, const pair<A, B>& a) {
  out << "(" << a.first << "," << a.second << ")";
  return out;
}
template <typename T, size_t N>
ostream& operator <<(ostream& out, const array<T, N>& a) {
  out << "["; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T>
ostream& operator <<(ostream& out, const vector<T>& a) {
  out << "["; bool first = true;
  for (auto v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "]";
  return out;
}
template <typename T, class Cmp>
ostream& operator <<(ostream& out, const set<T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& v : a) { out << (first ? "" : ", "); out << v; first = 0;} out << "}";
  return out;
}
template <typename U, typename T, class Cmp>
ostream& operator <<(ostream& out, const map<U, T, Cmp>& a) {
  out << "{"; bool first = true;
  for (auto& p : a) { out << (first ? "" : ", "); out << p.first << ":" << p.second; first = 0;} out << "}";
  return out;
}
#ifdef LOCAL
#define trace(...) __f(#__VA_ARGS__, __VA_ARGS__)
#else
#define trace(...) 42
#endif
template <typename Arg1>
void __f(const char* name, Arg1&& arg1){
  cerr << name << ": " << arg1 << endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args){
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << ": " << arg1 << " |";
  __f(comma + 1, args...);
}

template <class T> auto vect(const T& v, int n) { return vector<T>(n, v); }
template <class T, class... D> auto vect(const T& v, int n, D... m) {
  return vector<decltype(vect(v, m...))>(n, vect(v, m...));
}

typedef long long int64;
typedef pair<int, int> ii;
#define SZ(x) (int)((x).size())
template <typename T> static constexpr T inf = numeric_limits<T>::max() / 2;
// const int MOD = 1e9 + 7;
const int MOD = 998244353;
mt19937 mrand(random_device{}());
int rnd(int x) { return mrand() % x; }
// mt19937_64 mrand(random_device{}());
// int64 rnd(int64 x) { return mrand() % x; }
template <class T> void out(const vector<T>& a) { for (int i = 0; i < SZ(a); ++i) cout << a[i] << " \n"[i + 1 == SZ(a)]; }
template <class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template <class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
template <class T> void dedup(vector<T>& v) { sort(v.begin(), v.end()); v.erase(unique(v.begin(), v.end()), v.end()); }
void add(int& x, int y) { x += y; if (x >= MOD) x -= MOD; }

struct fast_ios {
  fast_ios() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
  };
} fast_ios_;

template <int MOD_> struct modnum {
  static constexpr int MOD = MOD_;
  static_assert(MOD_ > 0, "MOD must be positive");

 private:
  int v;
  static int minv(int a, int m) {
    a %= m; assert(a);
    return a == 1 ? 1 : int(m - int64(minv(m, a)) * int64(m) / a);
  }

 public:
  modnum() : v(0) {}
  modnum(int64 v_) : v(int(v_ % MOD)) { if (v < 0) v += MOD; }
  explicit operator int() const { return v; }
  friend std::ostream& operator << (std::ostream& out, const modnum& n) { return out << int(n); }
  friend std::istream& operator >> (std::istream& in, modnum& n) { int64 v_; in >> v_; n = modnum(v_); return in; }
  friend bool operator == (const modnum& a, const modnum& b) { return a.v == b.v; }
  friend bool operator != (const modnum& a, const modnum& b) { return a.v != b.v; }

  modnum inv() const { modnum res; res.v = minv(v, MOD); return res; }
  friend modnum inv(const modnum& m) { return m.inv(); }
  modnum neg() const { modnum res; res.v = v ? MOD-v : 0; return res; }
  friend modnum neg(const modnum& m) { return m.neg(); }

  modnum operator- () const { return neg(); }
  modnum operator+ () const { return modnum(*this); }

  modnum& operator ++ () { ++v; if (v == MOD) v = 0; return *this; }
  modnum& operator -- () { if (v == 0) v = MOD; --v; return *this; }
  modnum& operator += (const modnum& o) { v += o.v; if (v >= MOD) v -= MOD; return *this; }
  modnum& operator -= (const modnum& o) { v -= o.v; if (v < 0) v += MOD; return *this; }
  modnum& operator *= (const modnum& o) { v = int(int64(v) * int64(o.v) % MOD); return *this; }
  modnum& operator /= (const modnum& o) { return *this *= o.inv(); }

  friend modnum operator ++ (modnum& a, int) { modnum r = a; ++a; return r; }
  friend modnum operator -- (modnum& a, int) { modnum r = a; --a; return r; }
  friend modnum operator + (const modnum& a, const modnum& b) { return modnum(a) += b; }
  friend modnum operator - (const modnum& a, const modnum& b) { return modnum(a) -= b; }
  friend modnum operator * (const modnum& a, const modnum& b) { return modnum(a) *= b; }
  friend modnum operator / (const modnum& a, const modnum& b) { return modnum(a) /= b; }
  friend modnum power(modnum a, int64 n) {
    modnum ret = 1;
    for (; n; n >>= 1) {
      if (n & 1) ret *= a;
      a *= a;
    }
    return ret;
  }
};

using mint = modnum<MOD>;

template<typename T, size_t N>
struct fenwick {
  T c[N];
  fenwick() {
    fill(c + 1, c + N, 0);
  }
  void add(int x, T y) {
    for (; x < N; x += x & -x) {
      c[x] += y;
      if (c[x] >= MOD) c[x] -= MOD;
    }
  }
  T query(int x) {
    T ret = 0;
    for (; x; x -= x & -x) {
      ret += c[x];
      if (ret >= MOD) ret -= MOD;
    }
    return ret;
  }
};

int main() {
  int n;
  cin >> n;
  vector<int> a(n), A;
  for (auto& x : a) {
    cin >> x;
    A.push_back(x);
  }
  dedup(A);
  int m = SZ(A);

  auto solve =
    [&](const vector<int>& a, bool flag = 1) {
      int n = SZ(a);
      vector<int> L0(n), L1(n);
      const int N = 2e5 + 10;
      fenwick<int, N> F0, F1;
      for (int i = 0; i < n; ++i) {
        int x = lower_bound(A.begin(), A.end(), a[i]) - A.begin();
        if (flag) {
          x = m - x;
        } else {
          x += 1;
        }
        L0[i] = F0.query(x - 1);
        L1[i] = F1.query(x - 1);
        F0.add(x, 1);
        F1.add(x, a[i] % MOD);
      }
      return make_pair(L0, L1);
    };
  auto [L0, L1] = solve(a, 1);
  // trace(L0, L1);
  reverse(a.begin(), a.end());
  auto [R0, R1] = solve(a, 0);
  // trace(R0, R1);
  reverse(a.begin(), a.end());
  mint ret = 0;
  for (int i = 1; i < n - 1; ++i) {
    int j = n - 1 - i;
    auto cur = mint(a[i]) * L0[i] * R0[j] +
      mint(L1[i]) * R0[j] +
      mint(L0[i]) * R1[j];
    ret += cur;
  }
  cout << ret << '\n';
  return 0;
}