Cod sursa(job #2538958)
Utilizator | Hantig Lorena LorenaMaria | Data | 5 februarie 2020 13:55:46 |
---|---|---|---|
Problema | Invers modular | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.59 kb |
#include <fstream>
#define ll long long
using namespace std;
ifstream in("inversmodular.in");
ofstream out("inversmodular.out");
ll a,n;
ll putere(ll a,ll e)
{ ll p=1;
while(e>0)
{ if(e%2==0)
a*=a,a%=n,e/=2;
else
p*=a,p%=n,e--;
}
return p;
}
ll phi(ll x)
{ ll p=1;
for(ll i=2;i*i<=x;i++)
{ if(x%i!=0)
continue;
ll e=0,k=1;
while(x%i==0)
x/=i,e++,k*=i;
k/=i;
p=(i-1)*k;
}
if(x!=1)
p*=(x-1);
return p;
}
int main()
{ in>>a>>n;
out<<putere(a,phi(n)-1);
in.close();
out.close();
return 0;
}