verify/number-theory/LC_counting_primes.test.cpp

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Last update: 2025-10-21 21:13:36+09:00
Problem: https://judge.yosupo.jp/problem/counting_primes

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Code

#define PROBLEM "https://judge.yosupo.jp/problem/counting_primes"

#include "template/template.hpp"
#include "number-theory/prime-count.hpp"

int main() {
  ll n;
  in(n);
  out(PrimeCount::count(n));
}

#line 1 "verify/number-theory/LC_counting_primes.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/counting_primes"

#line 2 "template/template.hpp"
#include <bits/stdc++.h>
using namespace std;

#line 2 "template/macro.hpp"
#define rep(i, a, b) for (int i = (a); i < (int)(b); i++)
#define rrep(i, a, b) for (int i = (int)(b) - 1; i >= (a); i--)
#define ALL(v) (v).begin(), (v).end()
#define UNIQUE(v) sort(ALL(v)), (v).erase(unique(ALL(v)), (v).end())
#define SZ(v) (int)v.size()
#define MIN(v) *min_element(ALL(v))
#define MAX(v) *max_element(ALL(v))
#define LB(v, x) int(lower_bound(ALL(v), (x)) - (v).begin())
#define UB(v, x) int(upper_bound(ALL(v), (x)) - (v).begin())
#define YN(b) cout << ((b) ? "YES" : "NO") << "\n";
#define Yn(b) cout << ((b) ? "Yes" : "No") << "\n";
#define yn(b) cout << ((b) ? "yes" : "no") << "\n";
#line 6 "template/template.hpp"

#line 2 "template/util.hpp"
using uint = unsigned int;
using ll = long long int;
using ull = unsigned long long;
using i128 = __int128_t;
using u128 = __uint128_t;

template <class T, class S = T>
S SUM(const vector<T> &a) {
  return accumulate(ALL(a), S(0));
}
template <class T>
inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T>
inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

template <class T>
int popcnt(T x) {
  return __builtin_popcountll(x);
}
template <class T>
int topbit(T x) {
  return (x == 0 ? -1 : 63 - __builtin_clzll(x));
}
template <class T>
int lowbit(T x) {
  return (x == 0 ? -1 : __builtin_ctzll(x));
}
#line 8 "template/template.hpp"

#line 2 "template/inout.hpp"
struct Fast {
  Fast() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(15);
  }
} fast;

template <class T1, class T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
  return is >> p.first >> p.second;
}
template <class T1, class T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  return os << p.first << " " << p.second;
}
template <class T>
istream &operator>>(istream &is, vector<T> &a) {
  for (auto &v : a) is >> v;
  return is;
}
template <class T>
ostream &operator<<(ostream &os, const vector<T> &a) {
  for (auto it = a.begin(); it != a.end();) {
    os << *it;
    if (++it != a.end()) os << " ";
  }
  return os;
}
template <class T>
ostream &operator<<(ostream &os, const set<T> &st) {
  os << "{";
  for (auto it = st.begin(); it != st.end();) {
    os << *it;
    if (++it != st.end()) os << ",";
  }
  os << "}";
  return os;
}
template <class T1, class T2>
ostream &operator<<(ostream &os, const map<T1, T2> &mp) {
  os << "{";
  for (auto it = mp.begin(); it != mp.end();) {
    os << it->first << ":" << it->second;
    if (++it != mp.end()) os << ",";
  }
  os << "}";
  return os;
}

void in() {}
template <typename T, class... U>
void in(T &t, U &...u) {
  cin >> t;
  in(u...);
}
void out() { cout << "\n"; }
template <typename T, class... U, char sep = ' '>
void out(const T &t, const U &...u) {
  cout << t;
  if (sizeof...(u)) cout << sep;
  out(u...);
}
#line 10 "template/template.hpp"

#line 2 "template/debug.hpp"
#ifdef LOCAL
#define debug 1
#define show(...) _show(0, #__VA_ARGS__, __VA_ARGS__)
#else
#define debug 0
#define show(...) true
#endif
template <class T>
void _show(int i, T name) {
  cerr << '\n';
}
template <class T1, class T2, class... T3>
void _show(int i, const T1 &a, const T2 &b, const T3 &...c) {
  for (; a[i] != ',' && a[i] != '\0'; i++) cerr << a[i];
  cerr << ":" << b << " ";
  _show(i + 1, a, c...);
}
#line 2 "number-theory/prime-count.hpp"

namespace PrimeCount {
using i64 = int64_t;
static inline i64 div(i64 a, i64 b) { return double(a) / b; }
#define FUNC()                                                       \
  vector<i64> xs{0};                                                 \
  for (i64 i = N; i > 0; i = div(N, div(N, i) + 1)) xs.push_back(i); \
  vector<i64> cnt(xs);                                               \
  for (auto &x : cnt) --x;                                           \
  for (i64 x = 2, sq = sqrtl(N), xsz = xs.size(); x <= sq; ++x) {    \
    if (cnt[xsz - x] == cnt[xsz - x + 1]) continue;                  \
    i64 x2 = x * x, pi = cnt[xsz - x + 1];                           \
    for (i64 i = 1, n = xs[i]; i < xsz && n >= x2; n = xs[++i])      \
      cnt[i] -= cnt[i * x <= sq ? i * x : xsz - div(n, x)] - pi;     \
  }
pair<vector<i64>, vector<i64>> table(i64 N) {
  FUNC()
  return {xs, cnt};
}
i64 count(i64 N) {
  if (N < 2) return 0;
  FUNC()
  return cnt[1];
}
#undef FUNC
};  // namespace PrimeCount

/**
 * @brief 素数カウント
 * @docs docs/number-theory/prime-count.md
 */
#line 5 "verify/number-theory/LC_counting_primes.test.cpp"

int main() {
  ll n;
  in(n);
  out(PrimeCount::count(n));
}