Luzhiled's Library

This documentation is automatically generated by online-judge-tools/verification-helper

View the Project on GitHub ei1333/library

:heavy_check_mark: math/number-theory/fast-prime-factorization.hpp

Verified with

Code

namespace FastPrimeFactorization {

  template< typename word, typename dword, typename sword >
  struct UnsafeMod {
    UnsafeMod() : x(0) {}

    UnsafeMod(word _x) : x(init(_x)) {}

    bool operator==(const UnsafeMod &rhs) const {
      return x == rhs.x;
    }

    bool operator!=(const UnsafeMod &rhs) const {
      return x != rhs.x;
    }

    UnsafeMod &operator+=(const UnsafeMod &rhs) {
      if((x += rhs.x) >= mod) x -= mod;
      return *this;
    }

    UnsafeMod &operator-=(const UnsafeMod &rhs) {
      if(sword(x -= rhs.x) < 0) x += mod;
      return *this;
    }

    UnsafeMod &operator*=(const UnsafeMod &rhs) {
      x = reduce(dword(x) * rhs.x);
      return *this;
    }

    UnsafeMod operator+(const UnsafeMod &rhs) const {
      return UnsafeMod(*this) += rhs;
    }

    UnsafeMod operator-(const UnsafeMod &rhs) const {
      return UnsafeMod(*this) -= rhs;
    }

    UnsafeMod operator*(const UnsafeMod &rhs) const {
      return UnsafeMod(*this) *= rhs;
    }

    UnsafeMod pow(uint64_t e) const {
      UnsafeMod ret(1);
      for(UnsafeMod base = *this; e; e >>= 1, base *= base) {
        if(e & 1) ret *= base;
      }
      return ret;
    }

    word get() const {
      return reduce(x);
    }

    static constexpr int word_bits = sizeof(word) * 8;

    static word modulus() {
      return mod;
    }

    static word init(word w) {
      return reduce(dword(w) * r2);
    }

    static void set_mod(word m) {
      mod = m;
      inv = mul_inv(mod);
      r2 = -dword(mod) % mod;
    }

    static word reduce(dword x) {
      word y = word(x >> word_bits) - word((dword(word(x) * inv) * mod) >> word_bits);
      return sword(y) < 0 ? y + mod : y;
    }

    static word mul_inv(word n, int e = 6, word x = 1) {
      return !e ? x : mul_inv(n, e - 1, x * (2 - x * n));
    }

    static word mod, inv, r2;

    word x;
  };

  using uint128_t = __uint128_t;

  using Mod64 = UnsafeMod< uint64_t, uint128_t, int64_t >;
  template<> uint64_t Mod64::mod = 0;
  template<> uint64_t Mod64::inv = 0;
  template<> uint64_t Mod64::r2 = 0;

  using Mod32 = UnsafeMod< uint32_t, uint64_t, int32_t >;
  template<> uint32_t Mod32::mod = 0;
  template<> uint32_t Mod32::inv = 0;
  template<> uint32_t Mod32::r2 = 0;

  bool miller_rabin_primality_test_uint64(uint64_t n) {
    Mod64::set_mod(n);
    uint64_t d = n - 1;
    while(d % 2 == 0) d /= 2;
    Mod64 e{1}, rev{n - 1};
    // http://miller-rabin.appspot.com/  < 2^64
    for(uint64_t a : {2, 325, 9375, 28178, 450775, 9780504, 1795265022}) {
      if(n <= a) break;
      uint64_t t = d;
      Mod64 y = Mod64(a).pow(t);
      while(t != n - 1 && y != e && y != rev) {
        y *= y;
        t *= 2;
      }
      if(y != rev && t % 2 == 0) return false;
    }
    return true;
  }

  bool miller_rabin_primality_test_uint32(uint32_t n) {
    Mod32::set_mod(n);
    uint32_t d = n - 1;
    while(d % 2 == 0) d /= 2;
    Mod32 e{1}, rev{n - 1};
    for(uint32_t a : {2, 7, 61}) {
      if(n <= a) break;
      uint32_t t = d;
      Mod32 y = Mod32(a).pow(t);
      while(t != n - 1 && y != e && y != rev) {
        y *= y;
        t *= 2;
      }
      if(y != rev && t % 2 == 0) return false;
    }
    return true;
  }

  bool is_prime(uint64_t n) {
    if(n == 2) return true;
    if(n == 1 || n % 2 == 0) return false;
    if(n < uint64_t(1) << 31) return miller_rabin_primality_test_uint32(n);
    return miller_rabin_primality_test_uint64(n);
  }

  uint64_t pollard_rho(uint64_t n) {
    if(is_prime(n)) return n;
    if(n % 2 == 0) return 2;
    Mod64::set_mod(n);
    uint64_t d;
    Mod64 one{1};
    for(Mod64 c{one};; c += one) {
      Mod64 x{2}, y{2};
      do {
        x = x * x + c;
        y = y * y + c;
        y = y * y + c;
        d = __gcd((x - y).get(), n);
      } while(d == 1);
      if(d < n) return d;
    }
    assert(0);
  }

  vector< uint64_t > prime_factor(uint64_t n) {
    if(n <= 1) return {};
    uint64_t p = pollard_rho(n);
    if(p == n) return {p};
    auto l = prime_factor(p);
    auto r = prime_factor(n / p);
    copy(begin(r), end(r), back_inserter(l));
    return l;
  }
};
#line 1 "math/number-theory/fast-prime-factorization.hpp"
namespace FastPrimeFactorization {

  template< typename word, typename dword, typename sword >
  struct UnsafeMod {
    UnsafeMod() : x(0) {}

    UnsafeMod(word _x) : x(init(_x)) {}

    bool operator==(const UnsafeMod &rhs) const {
      return x == rhs.x;
    }

    bool operator!=(const UnsafeMod &rhs) const {
      return x != rhs.x;
    }

    UnsafeMod &operator+=(const UnsafeMod &rhs) {
      if((x += rhs.x) >= mod) x -= mod;
      return *this;
    }

    UnsafeMod &operator-=(const UnsafeMod &rhs) {
      if(sword(x -= rhs.x) < 0) x += mod;
      return *this;
    }

    UnsafeMod &operator*=(const UnsafeMod &rhs) {
      x = reduce(dword(x) * rhs.x);
      return *this;
    }

    UnsafeMod operator+(const UnsafeMod &rhs) const {
      return UnsafeMod(*this) += rhs;
    }

    UnsafeMod operator-(const UnsafeMod &rhs) const {
      return UnsafeMod(*this) -= rhs;
    }

    UnsafeMod operator*(const UnsafeMod &rhs) const {
      return UnsafeMod(*this) *= rhs;
    }

    UnsafeMod pow(uint64_t e) const {
      UnsafeMod ret(1);
      for(UnsafeMod base = *this; e; e >>= 1, base *= base) {
        if(e & 1) ret *= base;
      }
      return ret;
    }

    word get() const {
      return reduce(x);
    }

    static constexpr int word_bits = sizeof(word) * 8;

    static word modulus() {
      return mod;
    }

    static word init(word w) {
      return reduce(dword(w) * r2);
    }

    static void set_mod(word m) {
      mod = m;
      inv = mul_inv(mod);
      r2 = -dword(mod) % mod;
    }

    static word reduce(dword x) {
      word y = word(x >> word_bits) - word((dword(word(x) * inv) * mod) >> word_bits);
      return sword(y) < 0 ? y + mod : y;
    }

    static word mul_inv(word n, int e = 6, word x = 1) {
      return !e ? x : mul_inv(n, e - 1, x * (2 - x * n));
    }

    static word mod, inv, r2;

    word x;
  };

  using uint128_t = __uint128_t;

  using Mod64 = UnsafeMod< uint64_t, uint128_t, int64_t >;
  template<> uint64_t Mod64::mod = 0;
  template<> uint64_t Mod64::inv = 0;
  template<> uint64_t Mod64::r2 = 0;

  using Mod32 = UnsafeMod< uint32_t, uint64_t, int32_t >;
  template<> uint32_t Mod32::mod = 0;
  template<> uint32_t Mod32::inv = 0;
  template<> uint32_t Mod32::r2 = 0;

  bool miller_rabin_primality_test_uint64(uint64_t n) {
    Mod64::set_mod(n);
    uint64_t d = n - 1;
    while(d % 2 == 0) d /= 2;
    Mod64 e{1}, rev{n - 1};
    // http://miller-rabin.appspot.com/  < 2^64
    for(uint64_t a : {2, 325, 9375, 28178, 450775, 9780504, 1795265022}) {
      if(n <= a) break;
      uint64_t t = d;
      Mod64 y = Mod64(a).pow(t);
      while(t != n - 1 && y != e && y != rev) {
        y *= y;
        t *= 2;
      }
      if(y != rev && t % 2 == 0) return false;
    }
    return true;
  }

  bool miller_rabin_primality_test_uint32(uint32_t n) {
    Mod32::set_mod(n);
    uint32_t d = n - 1;
    while(d % 2 == 0) d /= 2;
    Mod32 e{1}, rev{n - 1};
    for(uint32_t a : {2, 7, 61}) {
      if(n <= a) break;
      uint32_t t = d;
      Mod32 y = Mod32(a).pow(t);
      while(t != n - 1 && y != e && y != rev) {
        y *= y;
        t *= 2;
      }
      if(y != rev && t % 2 == 0) return false;
    }
    return true;
  }

  bool is_prime(uint64_t n) {
    if(n == 2) return true;
    if(n == 1 || n % 2 == 0) return false;
    if(n < uint64_t(1) << 31) return miller_rabin_primality_test_uint32(n);
    return miller_rabin_primality_test_uint64(n);
  }

  uint64_t pollard_rho(uint64_t n) {
    if(is_prime(n)) return n;
    if(n % 2 == 0) return 2;
    Mod64::set_mod(n);
    uint64_t d;
    Mod64 one{1};
    for(Mod64 c{one};; c += one) {
      Mod64 x{2}, y{2};
      do {
        x = x * x + c;
        y = y * y + c;
        y = y * y + c;
        d = __gcd((x - y).get(), n);
      } while(d == 1);
      if(d < n) return d;
    }
    assert(0);
  }

  vector< uint64_t > prime_factor(uint64_t n) {
    if(n <= 1) return {};
    uint64_t p = pollard_rho(n);
    if(p == n) return {p};
    auto l = prime_factor(p);
    auto r = prime_factor(n / p);
    copy(begin(r), end(r), back_inserter(l));
    return l;
  }
};
Back to top page