Cod sursa(job #1787714)
Utilizator | Data | 24 octombrie 2016 22:17:43 | |
---|---|---|---|
Problema | Invers modular | Scor | 60 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.64 kb |
#include <stdio.h>
#define ll long long
using namespace std;
ll a,n,p,sol=1;
ll primus(ll n)
{
ll prim=n;
for(int i=2;i*i<=n;i++)
{
if(n%i==0)
{
while(n%i==0)n/i;
prim=prim/i*(i-1);
}
}
if(n!=1)
prim=prim/n*(n-1);
return prim;
}
int main()
{
freopen("inversmodular.in","r",stdin);
freopen("inversmodular.out","w",stdout);
scanf("%lld%lld",&a,&n);
p=primus(n)-1;
while(p)
{
if(p&1)
{
sol=((sol%n)*(a%n))%n;
}
a=((a%n)*(a%n))%n;
p>>=1;
}
printf("%lld",sol);
}