Pagini recente » Cod sursa (job #1902163) | Cod sursa (job #565197) | Cod sursa (job #3220993) | Cod sursa (job #622970) | Cod sursa (job #917969)
Cod sursa(job #917969)
#include <cstdio>
#include <iostream>
#include <vector>
using namespace std;
#define max_val 1000005
#define max_n 100005
#define FORIT( it,v ) for(typeof((v).begin()) it=(v).begin(); it!=(v).end(); ++it )
vector<int> Div, Desc;
bool Viz[max_val];
int Ap[max_val],El[max_n];
int n,i,j,c,nr,ind,rez,act;
void desc( int nr ){
int c=nr, d=0;
Desc.clear();
while( c!= 1 ){
if( c % Div[d] == 0 ){
Desc.push_back( Div[d] );
while( c%Div[d] == 0 ){
c/=Div[d];
}
}
d++;
}
}
int main(){
freopen("pairs.in","r",stdin);
freopen("pairs.out","w",stdout);
scanf("%d", &n );
for( i=1; i<=n; ++i ){
scanf("%d", &El[i] );
}
for( i=2; i<max_val; ++i ){
if( !Viz[i] ){
Div.push_back(i);
if( i-5<max_val/i )
for( j=i*i; j<max_val; j+=i ){
Viz[j]=1;
}
}
}
for( i=1; i<=n; ++i ){
desc( El[i] );
for( j=1; j<(1<<(Desc.size()) ); ++j ){
nr=1;
for( c=0; c<Desc.size(); ++c ){
if( j&(1<<c) ){
nr*=Desc[c];
}
}
Ap[nr]++;
}
}
for( i=1; i<=n; ++i ){
act=0;
desc( El[i] );
for( j=1; j< (1<<(Desc.size() )); ++j ){
ind=0;
nr=1;
for( c=0; c<Desc.size(); ++c ){
if( (1<<c)&j ){
ind++;
nr*=Desc[c];
}
}
if( (ind&1) )
act+=Ap[nr];
else
act-=Ap[nr];
}
rez+=n-act;
}
printf("%d\n",rez/2);
return 0;
}