結果

問題 No.2616 中央番目の中央値
ユーザー risujirohrisujiroh
提出日時 2024-01-26 21:39:44
言語 C++23
(gcc 12.3.0 + boost 1.83.0)
結果
AC  
実行時間 74 ms / 2,000 ms
コード長 7,668 bytes
コンパイル時間 3,596 ms
コンパイル使用メモリ 265,232 KB
実行使用メモリ 13,452 KB
最終ジャッジ日時 2024-09-28 07:53:19
合計ジャッジ時間 6,187 ms
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
（要ログイン）

テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 15 ms
10,880 KB
testcase_01 AC 15 ms
10,948 KB
testcase_02 AC 16 ms
10,900 KB
testcase_03 AC 15 ms
10,880 KB
testcase_04 AC 15 ms
10,956 KB
testcase_05 AC 15 ms
10,988 KB
testcase_06 AC 15 ms
11,008 KB
testcase_07 AC 15 ms
10,952 KB
testcase_08 AC 15 ms
10,880 KB
testcase_09 AC 14 ms
10,880 KB
testcase_10 AC 16 ms
10,880 KB
testcase_11 AC 15 ms
11,008 KB
testcase_12 AC 15 ms
10,892 KB
testcase_13 AC 15 ms
11,136 KB
testcase_14 AC 15 ms
10,952 KB
testcase_15 AC 16 ms
11,008 KB
testcase_16 AC 18 ms
11,196 KB
testcase_17 AC 19 ms
11,264 KB
testcase_18 AC 23 ms
11,392 KB
testcase_19 AC 31 ms
11,648 KB
testcase_20 AC 30 ms
11,776 KB
testcase_21 AC 50 ms
12,540 KB
testcase_22 AC 73 ms
13,248 KB
testcase_23 AC 70 ms
13,308 KB
testcase_24 AC 58 ms
13,312 KB
testcase_25 AC 56 ms
13,312 KB
testcase_26 AC 74 ms
13,312 KB
testcase_27 AC 71 ms
13,308 KB
testcase_28 AC 74 ms
13,440 KB
testcase_29 AC 72 ms
13,440 KB
testcase_30 AC 71 ms
13,440 KB
testcase_31 AC 72 ms
13,440 KB
testcase_32 AC 72 ms
13,304 KB
testcase_33 AC 71 ms
13,316 KB
testcase_34 AC 71 ms
13,452 KB
testcase_35 AC 71 ms
13,396 KB
testcase_36 AC 71 ms
13,320 KB
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 # 

#if __INCLUDE_LEVEL__ == 0

#include __BASE_FILE__

namespace {

using Fp = atcoder::modint998244353;

Comb<Fp> comb(1e6);

void solve() {
  int n;
  scan(n);
  std::vector<int> p(n);
  scan(p);
  --p;
  atcoder::fenwick_tree<int> f(n);
  Fp ans = 0;
  for (const int i : rep(n)) {
    const int ltL = f.sum(0, p[i]);
    const int gtL = i - ltL;
    const int ltR = p[i] - ltL;
    const int gtR = n - i - 1 - ltR;
    assert(ltL + gtL + ltR + gtR == n - 1);
    ans += comb.binom(ltL + gtR, ltL) * comb.binom(ltR + gtL, ltR);
    f.add(p[i], 1);
  }
  print(ans);
}

}  // namespace

int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);

  solve();
}

#else  // __INCLUDE_LEVEL__

#include <bits/stdc++.h>

#include <atcoder/fenwicktree>
#include <atcoder/modint>

template <class T>
std::vector<T> make_vector_for_overwrite(int n) {
  static_assert(std::is_trivially_destructible_v<T>);
  std::vector<T> v;
  static_assert(sizeof(v) == 3 * sizeof(T*));
  v.reserve(n);
  T*(&a)[3] = reinterpret_cast<T*(&)[3]>(v);
  assert(a[0] == a[1] && a[1] + n == a[2]);
  a[1] = a[2];
  return v;
}

template <class T>
class Comb {
 public:
  Comb() = default;

  explicit Comb(int max_n)
      : fact_(make_vector_for_overwrite<T>(max_n + 1)),
        recip_fact_(make_vector_for_overwrite<T>(max_n + 1)) {
    fact_[0] = 1;
    for (const int n : std::views::iota(1, max_n + 1)) {
      fact_[n] = fact_[n - 1] * n;
    }
    recip_fact_[max_n] = 1 / fact_[max_n];
    for (const int n : std::views::iota(1, max_n + 1) | std::views::reverse) {
      recip_fact_[n - 1] = n * recip_fact_[n];
    }
  }

  T recip(int n) const {
    assert(n);
    return n < 0 ? -recip(-n) : recip_fact_[n] * fact_[n - 1];
  }

  T fact(int n) const {
    assert(0 <= n);
    return fact_[n];
  }

  T recip_fact(int n) const { return n < 0 ? 0 : recip_fact_[n]; }

  T falling_fact(int n, int k) const {
    assert(0 <= n || n < k);
    if (n < 0) {
      const T t = falling_fact(k - n - 1, k);
      return k & 1 ? -t : t;
    }
    return n < k ? 0 : recip_fact(n - k) * fact(n);
  }

  T recip_falling_fact(int n, int k) const {
    assert(n < 0 || k <= n);
    return falling_fact(n - k, -k);
  }

  T rising_fact(int n, int k) const {
    assert(n <= 0 || 0 < n + k);
    return falling_fact(n + k - 1, k);
  }

  T recip_rising_fact(int n, int k) const {
    assert(0 < n || n + k <= 0);
    return falling_fact(n - 1, -k);
  }

  T binom(int n, int k) const {
    if ((n < 0) ^ (k < 0) ^ (n < k)) {
      return 0;
    }
    if (n < 0 && k < 0) {
      k = n - k;
    }
    return recip_fact(k) * falling_fact(n, k);
  }

  T recip_binom(int n, int k) const {
    assert((0 <= n) ^ (0 <= k) ^ (k <= n));
    k = std::max(k, n - k);
    return recip_falling_fact(n, k) * fact(k);
  }

  T multiset(int n, int k) const { return binom(n + k - 1, k); }

  T recip_multiset(int n, int k) const {
    assert((0 < n) ^ (0 <= k) ^ (0 < n + k));
    return recip_binom(n + k - 1, k);
  }

 private:
  std::vector<T> fact_;
  std::vector<T> recip_fact_;
};

template <class T, class U = T>
bool chmin(T& x, U&& y) {
  return y < x && (x = std::forward<U>(y), true);
}

template <class T, class U = T>
bool chmax(T& x, U&& y) {
  return x < y && (x = std::forward<U>(y), true);
}

template <std::signed_integral T = int>
T inf() {
  T ret;
  std::memset(&ret, 0x3f, sizeof(ret));
  return ret;
}

template <std::floating_point T>
T inf() {
  return std::numeric_limits<T>::infinity();
}

template <class T>
concept Range = std::ranges::range<T> && !std::convertible_to<T, std::string_view>;

template <class T>
concept Tuple = std::__is_tuple_like<T>::value && !Range<T>;

namespace std {

istream& operator>>(istream& is, Range auto&& r) {
  for (auto&& e : r) {
    is >> e;
  }
  return is;
}

istream& operator>>(istream& is, Tuple auto&& t) {
  return apply([&](auto&... xs) -> istream& { return (is >> ... >> xs); }, t);
}

ostream& operator<<(ostream& os, Range auto&& r) {
  for (string_view sep = ""; auto&& e : r) {
    os << exchange(sep, " ") << e;
  }
  return os;
}

ostream& operator<<(ostream& os, Tuple auto&& t) {
  const auto f = [&](auto&... xs) -> ostream& {
    [[maybe_unused]] string_view sep = "";
    ((os << exchange(sep, " ") << xs), ...);
    return os;
  };
  return apply(f, t);
}

template <class T, atcoder::internal::is_modint_t<T>* = nullptr>
istream& operator>>(istream& is, T& x) {
  int v;
  is >> v;
  x = T::raw(v);
  return is;
}

template <class T, atcoder::internal::is_modint_t<T>* = nullptr>
ostream& operator<<(ostream& os, const T& x) {
  return os << x.val();
}

}  // namespace std

#define DEF_INC_OR_DEC(op) \
  auto& operator op(Range auto&& r) { \
    for (auto&& e : r) { \
      op e; \
    } \
    return r; \
  } \
  auto& operator op(Tuple auto&& t) { \
    std::apply([](auto&... xs) { (op xs, ...); }, t); \
    return t; \
  }

DEF_INC_OR_DEC(++)
DEF_INC_OR_DEC(--)

#undef DEF_INC_OR_DEC

void scan(auto&&... xs) { std::cin >> std::tie(xs...); }
void print(auto&&... xs) { std::cout << std::tie(xs...) << '\n'; }

#define FWD(...) static_cast<decltype(__VA_ARGS__)&&>(__VA_ARGS__)

template <class F>
class fix {
 public:
  explicit fix(F f) : f_(std::move(f)) {}

  decltype(auto) operator()(auto&&... xs) const { return f_(std::ref(*this), FWD(xs)...); }

 private:
  F f_;
};

template <class T>
concept LambdaExpr = std::is_placeholder_v<std::remove_cvref_t<T>> != 0 ||
                     std::is_bind_expression_v<std::remove_cvref_t<T>>;

auto operator++(LambdaExpr auto&& x, int) {
  return std::bind([](auto&& x) -> decltype(auto) { return FWD(x)++; }, FWD(x));
}

auto operator--(LambdaExpr auto&& x, int) {
  return std::bind([](auto&& x) -> decltype(auto) { return FWD(x)--; }, FWD(x));
}

#define DEF_UNARY_OP(op) \
  auto operator op(LambdaExpr auto&& x) { \
    return std::bind([](auto&& x) -> decltype(auto) { return op FWD(x); }, FWD(x)); \
  }

DEF_UNARY_OP(++)
DEF_UNARY_OP(--)
DEF_UNARY_OP(+)
DEF_UNARY_OP(-)
DEF_UNARY_OP(~)
DEF_UNARY_OP(!)
DEF_UNARY_OP(*)
DEF_UNARY_OP(&)

#undef DEF_UNARY_OP

#define DEF_BINARY_OP(op) \
  template <class T1, class T2> \
    requires LambdaExpr<T1> || LambdaExpr<T2> \
  auto operator op(T1&& x, T2&& y) { \
    return std::bind([](auto&& x, auto&& y) -> decltype(auto) { return FWD(x) op FWD(y); }, \
                     FWD(x), FWD(y)); \
  }

DEF_BINARY_OP(+=)
DEF_BINARY_OP(-=)
DEF_BINARY_OP(*=)
DEF_BINARY_OP(/=)
DEF_BINARY_OP(%=)
DEF_BINARY_OP(^=)
DEF_BINARY_OP(&=)
DEF_BINARY_OP(|=)
DEF_BINARY_OP(<<=)
DEF_BINARY_OP(>>=)
DEF_BINARY_OP(+)
DEF_BINARY_OP(-)
DEF_BINARY_OP(*)
DEF_BINARY_OP(/)
DEF_BINARY_OP(%)
DEF_BINARY_OP(^)
DEF_BINARY_OP(&)
DEF_BINARY_OP(|)
DEF_BINARY_OP(<<)
DEF_BINARY_OP(>>)
DEF_BINARY_OP(==)
DEF_BINARY_OP(!=)
DEF_BINARY_OP(<)
DEF_BINARY_OP(>)
DEF_BINARY_OP(<=)
DEF_BINARY_OP(>=)
DEF_BINARY_OP(&&)
DEF_BINARY_OP(||)

#undef DEF_BINARY_OP

template <class T1, class T2>
  requires LambdaExpr<T1> || LambdaExpr<T2>
auto at(T1&& x, T2&& y) {
  return std::bind([](auto&& x, auto&& y) -> decltype(auto) { return FWD(x)[FWD(y)]; }, FWD(x),
                   FWD(y));
}

template <int I>
auto get(LambdaExpr auto&& x) {
  return std::bind([](auto&& x) -> decltype(auto) { return std::get<I>(FWD(x)); }, FWD(x));
}

inline auto rep(int l, int r) { return std::views::iota(std::min(l, r), r); }
inline auto rep(int n) { return rep(0, n); }
inline auto rep1(int l, int r) { return rep(l, r + 1); }
inline auto rep1(int n) { return rep(1, n + 1); }

using namespace std::literals;
using namespace std::placeholders;

namespace ranges = std::ranges;
namespace views = std::views;

using i64 = std::int64_t;

#endif  // __INCLUDE_LEVEL__
0