Cod sursa(job #1225620)
| Utilizator | Data | 3 septembrie 2014 03:16:07 | |
|---|---|---|---|
| Problema | Invers modular | Scor | 100 |
| Compilator | cpp | Status | done |
| Runda | Arhiva educationala | Marime | 0.64 kb |
#include <cstdio>
#include <cmath>
#include <iostream>
using namespace std;
long long a,n,x,nr,lim,sol,i;
int main()
{
freopen("inversmodular.in", "r", stdin);
freopen("inversmodular.out", "w", stdout);
scanf("%lld%lld",&a,&n);
x=nr=n;
lim=sqrt(n);
for(i=2;i<=lim;i++)
if(x%i==0)
{
//nr=nr*(i-1)/i;
nr-=nr/i;
while(x%i==0) x/=i;
}
//if(x>1) nr=nr*(x-1)/x;
if(x>1) nr-=nr/x;
nr--;
sol=1;
for(i=1;i<=nr;i<<=1)
{
if(nr&i) sol=(sol*a)%n;
a=(a*a)%n;
}
printf("%lld",sol);
return 0;
}
