std::vector<std::vector<int>> primeFactor(int n, const std::set<int>& primes)
{
std::vector<std::vector<int>> facs(n+1);
for (auto p:primes)
{
for(int i = 2*p; i <= n ; i += p)
facs[i].emplace_back(p);
}
std::function<void(int,int,int,const std::vector<int>&,std::vector<int>&)> tranverse = [&tranverse](int l,int i,int m,const std::vector<int>& f, std::vector<int>& lf)
{
if(l == 0)
{
lf.emplace_back(m);
return ;
}
else
{
for(int j = i+1 ; j <= f.size() - l ; ++ j)
tranverse(l-1,j,m*f[j],f,lf);
}
};
long whole_count = 0;
for (int i = 2 ; i <= n ; ++ i)
{
int count = i-1;
int t = -1;
for(int l = 1 ; l <= facs[i].size() ; ++ l)
{
std::vector<int> lf;
tranverse(l,-1,1,facs[i],lf);
for(auto f:lf)
count += t*(i/f-1);
t = -t;
}
whole_count+=count;
}
std::cout<<whole_count<<std::endl;
return facs;
}
char *change(int number, int base)
{
char *form;
form = (char *)malloc(20 * sizeof(char));
int i = 0;
do {
int c;
if(number % base < 10)
form[i++] = number % base + '0';
else
form[i++] = number % base - 10 + 'A';
} while(number /= base);
form[i] = '\0';
tranverse(form);
return form;
}
