hdu 5212 Code

#include<cstdio>
#include<vector>
#include<cstring>
#include<cstdio>
#include<algorithm>
using namespace std;
#define LL long long

const int maxn = 11234;
const int mod = 10007;

vector<int> fac[maxn];
LL mu[maxn];

void init(){
memset(mu,0,sizeof(mu));
mu[1] = 1;
for(int i=1;i<maxn;i++){
for(int j=i;j<maxn;j+=i){
fac[j].push_back(i);
if(j!=i) mu[j] -= mu[i];
}
}
}

LL cnt[maxn];

int main(){
init();
int n;
while(~scanf("%d",&n)){
memset(cnt,0,sizeof(cnt));
int x;
while(n--){
scanf("%d",&x);
for(vector<int>::iterator it = fac[x].begin();it!=fac[x].end();it++){
cnt[*it]++;
}
}
LL ret = 0;
for(int i=1;i<maxn;i++){
LL tim = 0;
for(int j=i;j<maxn;j+=i){
(tim += mu[j/i]*(cnt[j]*cnt[j])) %= mod;
}
ret += tim * i % mod * (i-1);
ret %= mod;
}
printf("%I64d\n",ret);
}
return 0;
}