Divisor Möbius Transform
(algorithm/divisor_mobius_transform.cpp)

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• Last update: 2020-09-11 14:24:32+09:00

Depends on

• other/ceildiv.cpp
• other/int_alias.cpp

Code

#include "other/ceildiv.cpp"
#include "other/int_alias.cpp"

#include <vector>

template <class G>
void divisor_mobius_transform(std::vector<typename G::value_type> &a) {
  const usize n = a.size();
  std::vector<bool> sieve(n, true);
  for (usize p = 2; p < n; p += 1) {
    if (!sieve[p])
      continue;
    for (usize k = ceildiv(n, p); k != 1;) {
      k -= 1;
      sieve[k * p] = false;
      a[k * p] = G::operation(G::inverse(a[k]), a[k * p]);
    }
  }
}

/**
 * @brief Divisor Möbius Transform
 */

#line 1 "other/ceildiv.cpp"
template <class T> constexpr T ceildiv(const T &n, const T &d) {
  return n / d + (n % d != 0 ? 1 : 0);
}
#line 2 "other/int_alias.cpp"

#include <cstddef>
#include <cstdint>

using i32 = std::int32_t;
using i64 = std::int64_t;
using u32 = std::uint32_t;
using u64 = std::uint64_t;
using isize = std::ptrdiff_t;
using usize = std::size_t;
#line 3 "algorithm/divisor_mobius_transform.cpp"

#include <vector>

template <class G>
void divisor_mobius_transform(std::vector<typename G::value_type> &a) {
  const usize n = a.size();
  std::vector<bool> sieve(n, true);
  for (usize p = 2; p < n; p += 1) {
    if (!sieve[p])
      continue;
    for (usize k = ceildiv(n, p); k != 1;) {
      k -= 1;
      sieve[k * p] = false;
      a[k * p] = G::operation(G::inverse(a[k]), a[k * p]);
    }
  }
}

/**
 * @brief Divisor Möbius Transform
 */

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