Cod sursa(job #2256623)

Utilizator georgitTreista Georgiana georgit Data 8 octombrie 2018 21:31:17
Problema Frac Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 1.23 kb
#include <fstream>
#define MAX 2000000
#define M 1e18

using namespace std;

int k,semn[MAX+5],n;
long long prod[MAX+5],v[MAX+5];
long long pozitie(long long a)
{
    int maxi=(1<<n);
    long long card=a;
    for(int i=1;i<maxi;i++)
        card=card+semn[i]*a/prod[i];
    return card;
}
int main()
{
    ifstream f("frac.in");
    ofstream g("frac.out");
    long long b,poz;
    f>>b>>poz;
    for(long long i=2;i*i<=b;i++)
        {
            if(b%i==0)
            {
                while(b%i==0)
                    b/=i;
                v[++n]=i;
            }
        }
        if(b>1)
            v[++n]=b;
        int maxi=(1<<n);
        for(int i=1;i<maxi;i++)
        {
            long long m=0;
            prod[i]=1;
            for(int j=0;j<n;j++)
                if((1<<j)&i)
                {
                    m++;
                    prod[i]*=v[j+1];
                }
            if(m%2==0)
                semn[i]=1;
            else
                semn[i]=-1;
        }
    long long st=1,dr=M;
    while(st<dr)
    {
        long long mij=(st+dr)/2;
        if(pozitie(mij)>=poz)
            dr=mij;
        else
            st=mij+1;
    }
    g<<st;

    return 0;
}