Cod sursa(job #1628365)
Utilizator | Data | 3 martie 2016 23:28:44 | |
---|---|---|---|
Problema | Invers modular | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.65 kb |
#include<cstdio>
#include<iostream>
#define ll long long
using namespace std;
ll n,a;
ll getphi(ll num)
{
int crt=num;
for(ll i=2; i*i<=num;i++)
{
if(num%i==0)
{
while(num%i==0) num/=i;
crt=(crt/i)*(i-1);
}
}
if(num!=1) crt=crt/num*(num-1);
return num;
}
int main()
{
freopen("inversmodular.in","r",stdin);
freopen("inversmodular.out","w",stdout);
scanf("%lld%lld",&a,&n);
ll put=getphi(n)-1;
ll sol=1;
for(ll i=1; i<=put; i<<=1)
{
if(i&put) sol=(sol*a)%n;
a=(a*a)%n;
}
cout<<sol<<'\n';
return 0;
}