test/verify/yosupo-discrete-logarithm-mod.test.cpp

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• Last update: 2024-04-22 02:14:31+09:00
• Problem: https://judge.yosupo.jp/problem/discrete_logarithm_mod

Depends on

• Mod Log(離散対数問題) (math/combinatorics/mod-log.hpp)
• template/template.hpp

Code

// competitive-verifier: PROBLEM https://judge.yosupo.jp/problem/discrete_logarithm_mod

#include "../../template/template.hpp"

#include "../../math/combinatorics/mod-log.hpp"

int main() {
  int T;
  cin >> T;
  while(T--) {
    int64_t X, Y, M;
    cin >> X >> Y >> M;
    cout << mod_log(X, Y, M) << endl;
  }
}

#line 1 "test/verify/yosupo-discrete-logarithm-mod.test.cpp"
// competitive-verifier: PROBLEM https://judge.yosupo.jp/problem/discrete_logarithm_mod

#line 1 "template/template.hpp"
#include<bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 1e9 + 7;

const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;

template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 >& p) {
  os << p.first << " " << p.second;
  return os;
}

template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
  is >> p.first >> p.second;
  return is;
}

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename F >
struct FixPoint : F {
  explicit FixPoint(F &&f) : F(forward< F >(f)) {}

  template< typename... Args >
  decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, forward< Args >(args)...);
  }
};
 
template< typename F >
inline decltype(auto) MFP(F &&f) {
  return FixPoint< F >{forward< F >(f)};
}
#line 4 "test/verify/yosupo-discrete-logarithm-mod.test.cpp"

#line 1 "math/combinatorics/mod-log.hpp"
/**
 * @brief Mod Log(離散対数問題)
 * 
 */
int64_t mod_log(int64_t a, int64_t b, int64_t p) {
  int64_t g = 1;

  for(int64_t i = p; i; i /= 2) (g *= a) %= p;
  g = __gcd(g, p);

  int64_t t = 1, c = 0;
  for(; t % g; c++) {
    if(t == b) return c;
    (t *= a) %= p;
  }
  if(b % g) return -1;

  t /= g;
  b /= g;

  int64_t n = p / g, h = 0, gs = 1;

  for(; h * h < n; h++) (gs *= a) %= n;

  unordered_map< int64_t, int64_t > bs;
  for(int64_t s = 0, e = b; s < h; bs[e] = ++s) {
    (e *= a) %= n;
  }

  for(int64_t s = 0, e = t; s < n;) {
    (e *= gs) %= n;
    s += h;
    if(bs.count(e)) return c + s - bs[e];
  }
  return -1;
}
#line 6 "test/verify/yosupo-discrete-logarithm-mod.test.cpp"

int main() {
  int T;
  cin >> T;
  while(T--) {
    int64_t X, Y, M;
    cin >> X >> Y >> M;
    cout << mod_log(X, Y, M) << endl;
  }
}

Test cases

Env	Name	Status	Elapsed	Memory
g++	even_mod_00	AC	151 ms	5 MB
g++	even_mod_01	AC	186 ms	5 MB
g++	even_mod_impossible_00	AC	6 ms	4 MB
g++	even_mod_impossible_01	AC	6 ms	4 MB
g++	example_00	AC	6 ms	4 MB
g++	max_random_00	AC	228 ms	5 MB
g++	max_random_01	AC	217 ms	5 MB
g++	max_random_02	AC	193 ms	5 MB
g++	random_00	AC	68 ms	5 MB
g++	random_01	AC	110 ms	5 MB
g++	random_02	AC	147 ms	5 MB
g++	small_00	AC	6 ms	4 MB
g++	small_01	AC	6 ms	4 MB
g++	small_02	AC	6 ms	4 MB
clang++	even_mod_00	AC	148 ms	5 MB
clang++	even_mod_01	AC	185 ms	5 MB
clang++	even_mod_impossible_00	AC	7 ms	4 MB
clang++	even_mod_impossible_01	AC	6 ms	4 MB
clang++	example_00	AC	6 ms	4 MB
clang++	max_random_00	AC	228 ms	5 MB
clang++	max_random_01	AC	216 ms	5 MB
clang++	max_random_02	AC	191 ms	5 MB
clang++	random_00	AC	68 ms	5 MB
clang++	random_01	AC	110 ms	5 MB
clang++	random_02	AC	146 ms	5 MB
clang++	small_00	AC	6 ms	4 MB
clang++	small_01	AC	6 ms	4 MB
clang++	small_02	AC	6 ms	4 MB

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