Cod sursa(job #1111012)
Utilizator | Data | 18 februarie 2014 16:21:11 | |
---|---|---|---|
Problema | Invers modular | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.5 kb |
#include<cstdio>
using namespace std;
long long a,b,c,n,i,phi,r;
int main()
{
freopen("inversmodular.in","r",stdin);
freopen("inversmodular.out","w",stdout);
scanf("%lld%lld",&a,&n); phi=1; c=n;
for(i=2;i*i<=n;i++)
if(n%i==0)
{
while(n%i==0) n/=i,phi*=i;
phi/=i; phi*=(i-1);
}
if(n>1) phi*=(n-1); b=phi-1; r=1;
for(i=1;i<=b;i<<=1)
{
if(i&b) r=(1LL*r*a)%c;
a=(1LL*a*a)%c;
}
printf("%lld\n",r);
return 0;
}