:heavy_check_mark: math/test/LC_mod_log.test.cpp

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Code

#define PROBLEM "https://judge.yosupo.jp/problem/discrete_logarithm_mod"
#include "../mod_log.hpp"
#include "../../util/template.hpp"

int main(){
    lint t;
    cin>>t;
    while(t--){
        lint x,y,p;
        cin>>x>>y>>p;
        cout<<mod_log(x,y,p)<<endl;
    }
}
#line 1 "math/test/LC_mod_log.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/discrete_logarithm_mod"
#line 1 "math/mod_pow.hpp"
/**
 * @brief (x^y)%mod
 */

long long mod_pow(long long x,long long y,long long mod){
    long long ret=1;
    while(y>0) {
        if(y&1)(ret*=x)%=mod;
        (x*=x)%=mod;
        y>>=1;
    }
    return ret;
}
#line 1 "math/euler_phi.hpp"
/**
 * @brief オイラーのファイ関数
 */

long long euler_phi(long long n) {
    long long ret = n;
    for(long long i=2;i*i<=n;i++) {
        if(n%i==0) {
            ret-=ret/i;
            while(n%i==0)n/=i;
        }
    }
    if(n>1)ret-=ret/n;
    return ret;
}
#line 4 "math/mod_log.hpp"
#include<map>
#include<numeric>
#include<cmath>

/**
 * @brief 離散対数(ModLog)
 */

long long mod_log(long long x,long long y,long long m){
    if(1==y||(x==0&&y==0&&m==1))return 0;
    if(x==0){
        if(y==1)return 0;
        if(y==0)return 1;
        else return -1;
    }
    long long _x=x,_y=y;
    long long g=m;
    long long cnt=0;
    while(std::gcd(x,m)!=1)m/=std::gcd(x,m),cnt++;
    g/=m;
    x%=m;
    y%=m;
    std::map<long long,long long>b;
    long long B=std::sqrt(m*g)+1;
    long long phi=euler_phi(m);
    long long a=mod_pow(x,B-1,m);
    long long inv_x=mod_pow(x,phi-1,m);
    for(long long i=B-1;i>=cnt;--i){
        b[a]=i;
        a=a*inv_x%m;
    }
    long long A=mod_pow(x,B*(phi-1),m);
    long long A2=y;
    for(long long i=0;i<B;++i){
        for(long long j=0;j<cnt;++j)if(mod_pow(_x,i*B+j,m*g)==_y)return i*B+j;
        if(b.count(A2)){
            if(mod_pow(_x,i*B+b[A2],m*g)==_y)return i*B+b[A2];
        }
        A2=A2*A%m;
    }
    return -1;
}
#line 2 "util/template.hpp"
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx2")
#include<bits/stdc++.h>
using namespace std;
struct __INIT__{__INIT__(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}}__INIT__;
typedef long long lint;
#define INF (1LL<<60)
#define IINF (1<<30)
#define EPS (1e-10)
#define endl ('\n')
typedef vector<lint> vec;
typedef vector<vector<lint>> mat;
typedef vector<vector<vector<lint>>> mat3;
typedef vector<string> svec;
typedef vector<vector<string>> smat;
template<typename T>using V=vector<T>;
template<typename T>using VV=V<V<T>>;
template<typename T>inline void output(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<<i;f=1;}cout<<endl;}
template<typename T>inline void output2(T t){for(auto i:t)output(i);}
template<typename T>inline void debug(T t){bool f=0;for(auto i:t){cerr<<(f?" ":"")<<i;f=1;}cerr<<endl;}
template<typename T>inline void debug2(T t){for(auto i:t)output(i);}
#define loop(n) for(long long _=0;_<(long long)(n);++_)
#define _overload4(_1,_2,_3,_4,name,...) name
#define __rep(i,a) repi(i,0,a,1)
#define _rep(i,a,b) repi(i,a,b,1)
#define repi(i,a,b,c) for(long long i=(long long)(a);i<(long long)(b);i+=c)
#define rep(...) _overload4(__VA_ARGS__,repi,_rep,__rep)(__VA_ARGS__)
#define _overload3_rev(_1,_2,_3,name,...) name
#define _rep_rev(i,a) repi_rev(i,0,a)
#define repi_rev(i,a,b) for(long long i=(long long)(b)-1;i>=(long long)(a);--i)
#define rrep(...) _overload3_rev(__VA_ARGS__,repi_rev,_rep_rev)(__VA_ARGS__)

// #define rep(i,...) for(auto i:range(__VA_ARGS__)) 
// #define rrep(i,...) for(auto i:reversed(range(__VA_ARGS__)))
// #define repi(i,a,b) for(lint i=lint(a);i<(lint)(b);++i)
// #define rrepi(i,a,b) for(lint i=lint(b)-1;i>=lint(a);--i)
// #define irep(i) for(lint i=0;;++i)
// inline vector<long long> range(long long n){if(n<=0)return vector<long long>();vector<long long>v(n);iota(v.begin(),v.end(),0LL);return v;}
// inline vector<long long> range(long long a,long long b){if(b<=a)return vector<long long>();vector<long long>v(b-a);iota(v.begin(),v.end(),a);return v;}
// inline vector<long long> range(long long a,long long b,long long c){if((b-a+c-1)/c<=0)return vector<long long>();vector<long long>v((b-a+c-1)/c);for(int i=0;i<(int)v.size();++i)v[i]=i?v[i-1]+c:a;return v;}
// template<typename T>inline T reversed(T v){reverse(v.begin(),v.end());return v;}
#define all(n) begin(n),end(n)
template<typename T,typename E>bool chmin(T& s,const E& t){bool res=s>t;s=min<T>(s,t);return res;}
template<typename T,typename E>bool chmax(T& s,const E& t){bool res=s<t;s=max<T>(s,t);return res;}
const vector<lint> dx={1,0,-1,0,1,1,-1,-1};
const vector<lint> dy={0,1,0,-1,1,-1,1,-1};
#define SUM(v) accumulate(all(v),0LL)
template<typename T,typename ...Args>auto make_vector(T x,int arg,Args ...args){if constexpr(sizeof...(args)==0)return vector<T>(arg,x);else return vector(arg,make_vector<T>(x,args...));}
#define extrep(v,...) for(auto v:__MAKE_MAT__({__VA_ARGS__}))
#define bit(n,a) ((n>>a)&1)
vector<vector<long long>> __MAKE_MAT__(vector<long long> v){if(v.empty())return vector<vector<long long>>(1,vector<long long>());long long n=v.back();v.pop_back();vector<vector<long long>> ret;vector<vector<long long>> tmp=__MAKE_MAT__(v);for(auto e:tmp)for(long long i=0;i<n;++i){ret.push_back(e);ret.back().push_back(i);}return ret;}
using graph=vector<vector<int>>;
template<typename T>using graph_w=vector<vector<pair<int,T>>>;
template<typename T,typename E>ostream& operator<<(ostream& out,pair<T,E>v){out<<"("<<v.first<<","<<v.second<<")";return out;}
constexpr inline long long powll(long long a,long long b){long long res=1;while(b--)res*=a;return res;}
#line 4 "math/test/LC_mod_log.test.cpp"

int main(){
    lint t;
    cin>>t;
    while(t--){
        lint x,y,p;
        cin>>x>>y>>p;
        cout<<mod_log(x,y,p)<<endl;
    }
}
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