Cod sursa(job #1787726)

Utilizator Costel_DraghiciDraghici Constantin Costel_Draghici Data 24 octombrie 2016 22:25:07
Problema Invers modular Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.65 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(ll i=2;i*i<=n;i++)
    {
        if(n%i==0)
        {
            while(n%i==0)n=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);
}