Pagini recente » Cod sursa (job #526502) | Cod sursa (job #2460324) | Cod sursa (job #1540094) | Cod sursa (job #526906) | Cod sursa (job #2559037)
#include <stdio.h>
#include <vector>
using namespace std;
FILE *fin = fopen("pairs.in", "r");
FILE *fout = fopen("pairs.out", "w");
vector <int> a[100005];
int n,i,x,d,nrfact[100005],prod,fr[1000005],val,j,k,nr,prime[100000],valmax,nrprime;
long long ans;
bool ciur[1000005];
int main()
{
valmax = 1000000;
for(i=2; i<=valmax; ++i)
if(!ciur[i])
{
prime[++nrprime] = i;
// fprintf(fout,"%d ",i);
for(j=i+i; j<=valmax; j+=i)
ciur[j] = 1;
}
fscanf(fin, "%d", &n);
for(i=1; i<=n; ++i)
{
fscanf(fin, "%d", &x);
j = 1;
while(prime[j]*prime[j] <= x)
{
if(x%prime[j] == 0)
{
nrfact[i]++;
a[i].push_back(prime[j]);
while(x%prime[j] == 0)
x /= prime[j];
}
++j;
}
if(x > 1)
{
nrfact[i]++;
a[i].push_back(x);
}
}
for(i=1; i<=n; ++i)
{
val = (1<<nrfact[i]) - 1;
for(j=1; j<=val; ++j)
{
prod = 1;
nr = 0;
for(k=0; k<nrfact[i]; ++k)
if(j & (1<<k))
{
prod *= a[i][k];
++nr;
}
fr[prod]++;
if(nr%2)
ans += 1LL*(fr[prod]-1LL);
else
ans -= 1LL*(fr[prod]-1LL);
}//for j
}
ans = 1LL*n*(n-1)/2LL - ans;
fprintf(fout, "%lld", ans);
fclose(fin);
fclose(fout);
return 0;
}