mmrz's library

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:heavy_check_mark: verify/yosupo/generalized_discrete_logarithm.test.cpp

Depends on

Code

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

#include "./../../template/template.hpp"
#include "./../../math/generalized_discrete_logarithm.hpp"
#include "./../../math/power.hpp"

using namespace mmrz;

void SOLVE(){
	ll x, y, m;
	cin >> x >> y >> m;

	auto f = [&x, &m](ll a) -> ll {
		return (a*x)%m;
	};

	int sq = sqrt(m);
	ll x_sq = power(x, sq, m);
	auto f_sq = [&x_sq, &m](ll a) -> ll {
		return (a*x_sq)%m;
	};

	cout << generalized_discrete_logarithm<int>(1%m, y, f, m, f_sq, sq) << '\n';
}

void mmrz::solve(){
	int t = 1;
	cin >> t;
	while(t--)SOLVE();
}
#line 1 "verify/yosupo/generalized_discrete_logarithm.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/discrete_logarithm_mod"

#line 1 "template/template.hpp"
# include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
const double pi = acos(-1);
template<class T>constexpr T inf() { return ::std::numeric_limits<T>::max(); }
template<class T>constexpr T hinf() { return inf<T>() / 2; }
template <typename T_char>T_char TL(T_char cX) { return tolower(cX); }
template <typename T_char>T_char TU(T_char cX) { return toupper(cX); }
template<class T> bool chmin(T& a,T b) { if(a > b){a = b; return true;} return false; }
template<class T> bool chmax(T& a,T b) { if(a < b){a = b; return true;} return false; }
int popcnt(unsigned long long n) { int cnt = 0; for (int i = 0; i < 64; i++)if ((n >> i) & 1)cnt++; return cnt; }
int d_sum(ll n) { int ret = 0; while (n > 0) { ret += n % 10; n /= 10; }return ret; }
int d_cnt(ll n) { int ret = 0; while (n > 0) { ret++; n /= 10; }return ret; }
ll gcd(ll a, ll b) { if (b == 0)return a; return gcd(b, a%b); };
ll lcm(ll a, ll b) { ll g = gcd(a, b); return a / g*b; };
ll MOD(ll x, ll m){return (x%m+m)%m; }
ll FLOOR(ll x, ll m) {ll r = (x%m+m)%m; return (x-r)/m; }
template<class T> using dijk = priority_queue<T, vector<T>, greater<T>>;
# define all(qpqpq)           (qpqpq).begin(),(qpqpq).end()
# define UNIQUE(wpwpw)        (wpwpw).erase(unique(all((wpwpw))),(wpwpw).end())
# define LOWER(epepe)         transform(all((epepe)),(epepe).begin(),TL<char>)
# define UPPER(rprpr)         transform(all((rprpr)),(rprpr).begin(),TU<char>)
# define rep(i,upupu)         for(ll i = 0, i##_len = (upupu);(i) < (i##_len);(i)++)
# define reps(i,opopo)        for(ll i = 1, i##_len = (opopo);(i) <= (i##_len);(i)++)
# define len(x)                ((ll)(x).size())
# define bit(n)               (1LL << (n))
# define pb push_back
# define eb emplace_back
# define exists(c, e)         ((c).find(e) != (c).end())

struct INIT{
	INIT(){
		std::ios::sync_with_stdio(false);
		std::cin.tie(0);
		cout << fixed << setprecision(20);
	}
}INIT;

namespace mmrz {
	void solve();
}

int main(){
	mmrz::solve();
}
#line 2 "math/generalized_discrete_logarithm.hpp"

#line 4 "math/generalized_discrete_logarithm.hpp"

template<typename T>
T generalized_discrete_logarithm(T x, T y, auto f, int n, auto f_m, int m){
	if(x == y){
		return 0;
	}

	std::unordered_set<T> baby_steps;
	T fy = y;
	for(int i = 0;i < m;i++){
		baby_steps.insert(fy);
		fy = f(fy);
	}

	T fx = x;
	bool is_first_loop = true;
	for(int i = 0;i <= n;i += m){
		T next_val = f_m(fx);
		if(baby_steps.contains(next_val)){
			for(int j = i+1;j <= i+m;j++){
				fx = f(fx);
				if(fx == y){
					return (j <= n ? j : -1);
				}
			}
			if(is_first_loop){
				is_first_loop = false;
			}else{
				return -1;
			}
		}
		fx = next_val;
	}
	return -1;
}
#line 2 "math/power.hpp"

#include <type_traits>

template<typename T>
concept NotPrimitiveInt =
	!(std::is_same_v<T, int> ||
		std::is_same_v<T, long> ||
		std::is_same_v<T, long long> ||
		std::is_same_v<T, unsigned> ||
		std::is_same_v<T, unsigned long> ||
		std::is_same_v<T, unsigned long long>);

template<NotPrimitiveInt T>
T power(T n, long long k) {
	T ret = 1;
	while(k > 0) {
		if(k & 1)ret *= n;
		n = n*n;
		k >>= 1;
	}
	return ret;
}

long long power(long long n, long long k, long long p) {
	long long ret = 1;
	while(k > 0){
		if(k & 1)ret = ret*n % p;
		n = n*n % p;
		k >>= 1;
	}
	return ret;
}
#line 6 "verify/yosupo/generalized_discrete_logarithm.test.cpp"

using namespace mmrz;

void SOLVE(){
	ll x, y, m;
	cin >> x >> y >> m;

	auto f = [&x, &m](ll a) -> ll {
		return (a*x)%m;
	};

	int sq = sqrt(m);
	ll x_sq = power(x, sq, m);
	auto f_sq = [&x_sq, &m](ll a) -> ll {
		return (a*x_sq)%m;
	};

	cout << generalized_discrete_logarithm<int>(1%m, y, f, m, f_sq, sq) << '\n';
}

void mmrz::solve(){
	int t = 1;
	cin >> t;
	while(t--)SOLVE();
}
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