#512689 (C++17) No.1115 二つの数列 / Two Sequences

• 問題: No.1115 二つの数列 / Two Sequences
• ユーザー: keijak
• 提出日時: 2020-07-17 21:26:54
• 言語: C++17 (gcc 13.3.0 + boost 1.87.0)
• 結果: AC
• 実行時間: 67 ms / 2,000 ms
• コード長: 2,636 bytes
• コンパイル時間: 3,632 ms
• コンパイル使用メモリ: 197,856 KB
• 最終ジャッジ日時: 2025-01-11 22:06:20
• ジャッジサーバーID （参考情報）: judge1 / judge4

ファイルパターン	結果
sample	AC * 5
other	AC * 35

ソースコード

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#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
using u64 = unsigned long long;
#define REP(i, n) for (int i = 0; (i64)(i) < (i64)(n); ++i)
#ifdef ENABLE_DEBUG
template <typename T>
void debug(T value) {
  cerr << value;
}
template <typename T, typename... Ts>
void debug(T value, Ts... args) {
  cerr << value << ", ";
  debug(args...);
}
#define DEBUG(...)                              \
  do {                                          \
    cerr << " \033[33m (L" << __LINE__ << ") "; \
    cerr << #__VA_ARGS__ << ":\033[0m ";        \
    debug(__VA_ARGS__);                         \
    cerr << endl;                               \
  } while (0)
#else
#define debug(...)
#define DEBUG(...)
#endif
template <class Monoid>
struct SegTree {
  using Func = function<Monoid(Monoid, Monoid)>;
  const Func F;
  const Monoid UNITY;
  int size;
  vector<Monoid> dat;
  SegTree(int n, const Func f, const Monoid &unity)
      : F(f), UNITY(unity), size(n), dat(2 * n, unity) {}
  // Sets i-th value (0-indexed) to x for initial setup.
  // build() must be called after set() calls.
  void set(int i, const Monoid &x) { dat[size + i] = x; }
  void build() {
    for (int k = size - 1; k > 0; --k) {
      dat[k] = F(dat[k * 2], dat[k * 2 + 1]);
    }
  }
  // Sets i-th value (0-indexed) to x.
  void update(int i, const Monoid &x) {
    int k = size + i;
    dat[k] = x;
    while (k > 1) {
      k >>= 1;
      dat[k] = F(dat[k * 2], dat[k * 2 + 1]);
    }
  }
  // Queries by [l,r) range (0-indexed, open interval).
  Monoid fold(int l, int r) {
    l += size;
    r += size;
    Monoid vleft = UNITY, vright = UNITY;
    for (; l < r; l >>= 1, r >>= 1) {
      if (l & 1) vleft = F(vleft, dat[l++]);
      if (r & 1) vright = F(dat[--r], vright);
    }
    return F(vleft, vright);
  }
  // Queries by a single index (0-indexed).
  Monoid operator[](int i) { return dat[size + i]; }
  /* debug */
  void print() {
    for (int i = 0; i < size; ++i) {
      cout << (*this)[i];
      if (i != size - 1) cout << ",";
    }
    cout << endl;
  }
};
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int n;
  cin >> n;
  vector<int> A(n), B(n);
  for (auto &x : A) {
    cin >> x;
    --x;
  }
  for (auto &x : B) {
    cin >> x;
    --x;
  }
  vector<int> ar(n), br(n);
  REP(i, n) {
    ar[A[i]] = i;
    br[B[i]] = i;
  }
  SegTree<i64> ast(
      n, [](i64 x, i64 y) { return x + y; }, 0LL);
  REP(i, n) { ast.set(i, 1); }
  ast.build();
  i64 steps = 0;
  REP(i, n) {
    int k = ar[B[i]];
    i64 s = ast.fold(0, k);
    steps += s;
    ast.update(k, 0);
  }
  cout << steps << endl;
}
 
 
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