Cod sursa(job #2248084)

Utilizator maria_neagoieMaria Neagoie maria_neagoie Data 29 septembrie 2018 11:20:33
Problema Invers modular Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.75 kb
#include <cstdio>
using namespace std;
int euler(int n)
{
    int d,e,phi=n;
    d=2;
    while(d*d<=n && n>1)
    {
        e=0;
        while(n%d==0)
        {
            e++;
            n=n/d;
        }
        if(e)
            phi=phi/d*(d-1);
        d++;
    }
    if(n>1)
        phi=phi/n*(n-1);
    return phi;
}
int putere(int a,int n,int m)
{
    int p=1;
    do
    {
        if(n%2==1)
            p=(long long)p*a%m;
        a=(long long)a*a%m;
        n=n/2;
    }
    while(n);
    return p;
}
int main()
{
    freopen("inversmodular.in","r",stdin);
    freopen("inversmodular.out","w",stdout);
    int a,n,phi;
    scanf("%d%d",&a,&n);
    phi=euler(n);
    printf("%d",putere(a,phi-1,n));
    return 0;
}