#585930 (C++17) No.1300 Sum of Inversions

• 問題: No.1300 Sum of Inversions
• ユーザー: mai
• 提出日時: 2020-11-27 23:19:15
• 言語: C++17 (gcc 13.3.0 + boost 1.87.0)
• 結果: WA
• 実行時間: -
• コード長: 9,937 bytes
• コンパイル時間: 2,355 ms
• コンパイル使用メモリ: 221,280 KB
• 最終ジャッジ日時: 2025-01-16 08:31:27
• ジャッジサーバーID （参考情報）: judge5 / judge2

ファイルパターン	結果
sample	WA * 3
other	AC * 1 WA * 33

ソースコード

#pragma GCC optimize ("O3")
#include <bits/stdc++.h>

using namespace std;
using ll = long long int;

#define all(v) (v).begin(),(v).end()
#define repeat(cnt,l) for(typename remove_const<typename remove_reference<decltype(l)>::type>::type cnt={};(cnt)<(l);++(cnt))
#define rrepeat(cnt,l) for(auto cnt=(l)-1;0<=(cnt);--(cnt))
#define iterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);++(cnt))
#define diterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);--(cnt))
const long long MD = 1000000007ll; const long double PI = 3.1415926535897932384626433832795L;
template<typename T1, typename T2> inline ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << '(' << p.first << ':' << p.second << ')'; return o; }
template<typename T> inline T& chmax(T& to, const T& val) { return to = max(to, val); }
template<typename T> inline T& chmin(T& to, const T& val) { return to = min(to, val); }
void bye(string s, int code = 0) { cout << s << endl; exit(code); }
mt19937_64 randdev(8901016);
template<typename T, typename Random = decltype(randdev), typename enable_if<is_integral<T>::value>::type* = nullptr>
inline T rand(T l, T h, Random& rand = randdev) { return uniform_int_distribution<T>(l, h)(rand); }
template<typename T, typename Random = decltype(randdev), typename enable_if<is_floating_point<T>::value>::type* = nullptr>
inline T rand(T l, T h, Random& rand = randdev) { return uniform_real_distribution<T>(l, h)(rand); }template<typename T>
static ostream& operator<<(ostream& o, const std::vector<T>& v) {
  o << "[ "; for(const auto& e : v) o<<e<<' ';
  return o << ']';
}

template <typename I>
struct MyRangeFormat{ I b,e; MyRangeFormat(I _b, I _e):b(_b),e(_e){} };
template<typename I>
static ostream& operator<<(ostream& o, const MyRangeFormat<I>& f) {
  o << "[ "; iterate(i,f.b,f.e) o<<*i<<' ';
  return o << ']';
}
template <typename I>
struct MyMatrixFormat{
  const I& p; long long n, m;
  MyMatrixFormat(const I& _p, long long _n, long long _m):p(_p),n(_n),m(_m){}
};
template<typename I>
static ostream& operator<<(ostream& o, const MyMatrixFormat<I>& f) {
  o<<'\n';
  repeat(i,(f.n)) {
    repeat(j,f.m) o<<f.p[i][j]<<' ';
    o<<'\n';
  }
  return o;
}
struct LOG_t { ~LOG_t() { cout << endl; } };
#define LOG (LOG_t(),cout<<'L'<<__LINE__<<": ")
#define FMTA(m,w) (MyRangeFormat<decltype(m+0)>(m,m+w))
#define FMTR(b,e) (MyRangeFormat<decltype(e)>(b,e))
#define FMTV(v) FMTR(v.begin(),v.end())
#define FMTM(m,h,w) (MyMatrixFormat<decltype(m+0)>(m,h,w))

#if defined(_WIN32) || defined(_WIN64)
#define getc_x _getc_nolock
#define putc_x _putc_nolock
#elif defined(__GNUC__)
#define getc_x getc_unlocked
#define putc_x putc_unlocked
#else
#define getc_x getc
#define putc_x putc
#endif
class MaiScanner {
  FILE* fp_;
  constexpr bool isvisiblechar(char c) noexcept { return (0x21<=(c)&&(c)<=0x7E); }
public:
  inline MaiScanner(FILE* fp):fp_(fp){}
  template<typename T> void input_integer(T& var) noexcept {
    var = 0; T sign = 1;
    int cc = getc_x(fp_);
    for (; cc < '0' || '9' < cc; cc = getc_x(fp_))
      if (cc == '-') sign = -1;
    for (; '0' <= cc && cc <= '9'; cc = getc_x(fp_))
      var = (var << 3) + (var << 1) + cc - '0';
    var = var * sign;
  }
  inline int c() noexcept { return getc_x(fp_); }
  template<typename T, typename enable_if<is_integral<T>::value, nullptr_t>::type = nullptr>
  inline MaiScanner& operator>>(T& var) noexcept { input_integer<T>(var); return *this; }
  inline MaiScanner& operator>>(string& var) {
    int cc = getc_x(fp_);
    for (; !isvisiblechar(cc); cc = getc_x(fp_));
    for (; isvisiblechar(cc); cc = getc_x(fp_))
      var.push_back(cc);
    return *this;
  }
  template<typename IT> inline void in(IT begin, IT end) { for (auto it = begin; it != end; ++it) *this >> *it; }
};
class MaiPrinter {
  FILE* fp_;
public:
  inline MaiPrinter(FILE* fp):fp_(fp){}
  template<typename T>
  void output_integer(T var) noexcept {
    if (var == 0) { putc_x('0', fp_); return; }
    if (var < 0)
      putc_x('-', fp_),
      var = -var;
    char stack[32]; int stack_p = 0;
    while (var)
      stack[stack_p++] = '0' + (var % 10),
      var /= 10;
    while (stack_p)
      putc_x(stack[--stack_p], fp_);
  }
  inline MaiPrinter& operator<<(char c) noexcept { putc_x(c, fp_); return *this; }
  template<typename T, typename enable_if<is_integral<T>::value, nullptr_t>::type = nullptr>
  inline MaiPrinter& operator<<(T var) noexcept { output_integer<T>(var); return *this; }
  inline MaiPrinter& operator<<(char* str_p) noexcept { while (*str_p) putc_x(*(str_p++), fp_); return *this; }
  inline MaiPrinter& operator<<(const string& str) {
    const char* p = str.c_str();
    const char* l = p + str.size();
    while (p < l) putc_x(*p++, fp_);
    return *this;
  }
  template<typename IT> void join(IT begin, IT end, char sep = ' ') { for (bool b = 0; begin != end; ++begin, b = 1) b ? *this << sep << *begin : *this << *begin; }
};
MaiScanner scanner(stdin);
MaiPrinter printer(stdout);

template <typename T = long long>
class Bitree {
  const int size_;
  vector<T> data_;
  static int nlz(uint32_t x) {
    union {
      uint32_t i;
      float f;
    } data;
    data.f = (float)x + 0.5;
    return 158 - (data.i >> 23);
  }

 public:
  Bitree(int size_) : size_(size_), data_(size_ + 1) {}

  // 1..rの範囲の値の和を求める．
  T sum(int r) const {
    T s = 0;
    while (r) {
      s += data_[r];
      r -= r & -r;  //  r&-r と書くことで最下のビットを得る
    }
    return s;
  }
  // l..rの範囲の値の和を求める
  inline T sum(int l, int r) const { return sum(r) - sum(l - 1); }
  // i番目の値を求める(1index)
  T get(int i) const {
    int j = i - 1;
    T s = 0;
    while (i != j) {
      s += data_[i] - data_[j];
      i -= i & -i;
      j -= j & -j;
    }
    return s;
  }
  // idxの要素の値をval増やす
  void add(int idx, T val) {
    while (idx <= size_) {
      data_[idx] += val;
      idx += idx & -idx;
    }
  }
  // sum(i)がvalを超える最初のiを返す
  // get(j)<0となるjが存在すると正しく動作しない
  int upper_bound(T val) const {
    int li = 1 << (31 - nlz(size_));
    int p = 0;
    T d = 0;
    while (li && p < size_) {
      T k = data_[p | li];
      if (!(val < d + k))
        p |= li, d += k;
      li >>= 1;
    }
    if (p > size_)
      p = size_;
    return p + 1;
  }
  // sum(i)がval以上である最初のiを返す
  // get(j)<0となるjが存在すると正しく動作しない
  int lower_bound(T val) const {
    int li = 1 << (31 - nlz(size_));
    int p = 0;
    T d = 0;
    while (li && p < size_) {
      T k = data_[p | li];
      if (d + k < val)
        p |= li, d += k;
      li >>= 1;
    }
    if (p > size_)
      p = size_;
    return p + 1;
  }
};

class llmod {
 private:
  using value_type = long long;
  value_type val_;
  // inline ll cut(ll v) const { return ((v%MOD) + MOD) % MOD; } // safe
 public:
  static const value_type MOD = 1000000007;  // <=

  llmod() : val_(0) {}
  llmod(value_type num) : val_(((num % MOD) + MOD) % MOD) {}

  inline operator value_type() const { return val_; }
  inline value_type operator*() const { return val_; }
  inline llmod& operator=(const llmod& lm) {
    val_ = lm.val_;
    return *this;
  }
  inline llmod& operator=(value_type v) {
    val_ = (v) % MOD;
    return *this;
  }

  inline llmod& operator+=(value_type v) {
    val_ = (val_ + v) % MOD;
    return *this;
  }
  inline llmod& operator+=(const llmod& l) {
    val_ = (val_ + l.val_) % MOD;
    return *this;
  }
  inline llmod& operator-=(value_type v) {
    val_ = (val_ - v + MOD) % MOD;
    return *this;
  }
  inline llmod& operator-=(const llmod& l) {
    val_ = (val_ - l.val_ + MOD) % MOD;
    return *this;
  }
  inline llmod& operator*=(value_type v) {
    val_ = (val_ * v) % MOD;
    return *this;
  }
  inline llmod& operator*=(const llmod& l) {
    val_ = (val_ * l.val_) % MOD;
    return *this;
  }
  inline llmod& operator++() {
    val_ = (val_ + 1) % MOD;
    return *this;
  }
  inline llmod operator++(int) {
    llmod t = *this;
    val_ = (val_ + 1) % MOD;
    return t;
  }
  inline llmod& justify() {
    val_ = ((val_ % MOD) + MOD) % MOD;
    return *this;
  }
  friend llmod pow(llmod, long long);
};
inline std::ostream& operator<<(std::ostream& os, const llmod& l) {
  os << *l;
  return os;
}

inline llmod operator+(llmod t, const llmod& r) {
  return t += r;
}
inline llmod operator-(llmod t, const llmod& r) {
  return t -= r;
}
inline llmod operator*(llmod t, const llmod& r) {
  return t *= r;
}

// MEMO : 逆元...pow(n,MD-2)
llmod pow(llmod x, long long p) {
  llmod::value_type y = 1;
  llmod::value_type xval = x.justify();
  while (0 < p) {
    if (p & 1)
      y = (xval * y) % llmod::MOD;
    xval = (xval * xval) % llmod::MOD;
    p >>= 1;
  }
  return llmod(y);
}

inline llmod& operator/=(llmod& l, const llmod& r) {
  return l *= pow(r, llmod::MOD - 2);
}

// ソートしてi番目の値は 元々idx[i]番目の値
// 元々i番目の値は ソートするとidxr[i]番目の値
template <typename ITER>
void sortedIndex(const ITER begin, const ITER end, vector<int>& idx, vector<int>& idxr) {
  size_t n = end - begin;
  idx.resize(n);
  idxr.resize(n);
  for (int i = 0; i < n; ++i)
    idx[i] = i;
  sort(idx.begin(), idx.end(), [&begin](int l, int r) { return begin[l] < begin[r]; });
  for (int i = 0; i < n; ++i)
    idxr[idx[i]] = i;
}

//

int N;
ll A[200010];

//

int main() {
  scanner >> N;
  scanner.in(A, A+N);
  
  vector<int> aidx, aidxr;
  sortedIndex(A, A+N, aidx, aidxr);
  
  Bitree<llmod> bit1(N);
  
  llmod total = 0;
  for (int i : aidx) {
    total += bit1.sum(i+1, N);
    // LOG << i << ' ' << A[i] << ' ' << *total;
    bit1.add(i+1, A[i]);
  }
  
  Bitree<llmod> bit2(N);
  iterate(it, aidx.rbegin(), aidx.rend()) {
    auto i = *it;
    bit1.add(i+1, A[i]);
    total += bit2.sum(i+1);
  }
  
  cout << *total << endl;
  
  return 0;
}