Cod sursa(job #3255443)

Utilizator Robert_MitriRobert Mitri Robert_Mitri Data 10 noiembrie 2024 17:09:51
Problema Pairs Scor 10
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 2.58 kb
#define ne

#ifdef ne
#include <fstream>
#include <vector>
#include <algorithm>
#include <cmath>
using namespace std;
ifstream fin("pairs.in");
ofstream fout("pairs.out");

const int valmax = 1000000;
long long n;

long long sol;

bool f[valmax + 5];
long long x[valmax + 5];
long long dz[1005];

bool p[valmax + 5];

long long b[16];

void bk(int pas,long long prod){
    if(pas!=1)
    {
        if(pas%2)
            sol-=(1LL*x[prod]*(x[prod]-1))/2;
        else
            sol+=(1LL*x[prod]*(x[prod]-1))/2;
    }
    for(int i = b[pas-1] + 1;i<=dz[0];i++){
        b[pas]=i;
        if(prod * dz[i] <=valmax)
            bk(pas+1,prod*dz[i]);
    }

}

void preprocess()
{
    p[0]=p[1]=true;
    int q = 1000;
    for(int i = 2; i<=q;i++)
        if(!p[i]){
            dz[++dz[0]]=i;
            for(int j = 2* i;j<=q;j+=i)
                p[j]=true;
        }
}


int main()
{
    preprocess();
    fin>>n;
    for(int i=1;i<=n;i++)
    {
        int x;
        fin>>x;
        f[x]=true;
    }
    for(int i=2;i<=valmax;i++)
        for(int j = i;j<=valmax;j+=i)
            x[i]+=f[j];
    bk(1,1);
    fout<<n*(n-1)/2-sol;
}

#else

#include <fstream>
#include <vector>
#include <algorithm>
using namespace std;
ifstream fin("pairs.in");
ofstream fout("pairs.out");

const int valmax = 1000000;
const int sqvalmax = 1000;
const int nmax = 100000;

int n;

int v[nmax + 5];
bool c[sqvalmax+5];
vector <int> dvz;
int bk[16];
int nr[16];
long long sol;
int tot[valmax + 5];

void prim()
{
    c[0]=1;
    c[1]=1;
    for(int i=2; i<=sqvalmax; i++)
        if(!c[i])
        {
            dvz.push_back(i);
            for(int j=i*2; j<=sqvalmax; j+=i)
                c[j]=true;
        }
}

void desc(int val)
{
    nr[0]=0;
    for(auto& j : dvz)
    {
        if(j*j>val)
            break;
        if(val%j==0)
        {
            while(val%j==0)
                val/=j;
            nr[++nr[0]] = j;
        }
    }
    if(val!=1)
        nr[++nr[0]]=val;
}
void bkt(int pas,long long prod = 1)
{
    if(prod!=1)
    {
        if(pas%2)
            sol+=tot[prod];
        else
            sol-=tot[prod];
        tot[prod]++;
    }
    if(pas==nr[0]+1)
        return;
    for(int i = bk[pas-1]+1; i<=nr[0]; i++)
    {
        bk[pas]=i;
        bkt(pas+1,prod*nr[bk[pas]]);
    }
}




int main()
{
    prim();
    fin>>n;
    for(int i=1; i<=n; i++)
    {
        sol+=i-1;
        fin>>v[i];
        desc(v[i]);
        bkt(1);
    }
    fout<<sol;

}
#endif