1 #include<stdio.h>
2 #include<string.h>
3 int x,t[100005],d[100005];
4 int f[100005][10],a[100005];
5 int vis[355],prime[355];
6 void dfs1(int tt,int now,int bei)
7 {
8 d[bei]++;
9 for (int i=now+1;i<=t[tt];i++)
10 dfs1(tt,i,f[tt][i]*bei);
11 }
12 void dfs2(int tt,int now,int flag,int bei)
13 {
14 if (flag) x+=d[bei];
15 else x-=d[bei];
16 for (int i=now+1;i<=t[tt];i++)
17 dfs2(tt,i,1-flag,f[tt][i]*bei);
18 }
19 int main()
20 {
21 int cnt=0,i,j,T,n,y;
22 long long ans;
23 memset(vis,0,sizeof(vis));
24 for (i=2;i<=320;i++)
25 if (vis[i]==0){
26 cnt++;
27 prime[cnt]=i;
28 for (j=2;i*j<=320;j++) vis[i*j]=1;
29 }
30 scanf("%d",&T);
31 while (T--)
32 {
33 scanf("%d",&n);
34 for (i=1;i<=n;i++) scanf("%d",&a[i]);
35 memset(d,0,sizeof(d));
36 for (i=1;i<=n;i++)
37 {
38 x=a[i]; t[i]=0;
39 for (j=1;j<=cnt;j++)
40 {
41 if (prime[j]>x) break;
42 if (x%prime[j]==0) {t[i]++; f[i][t[i]]=prime[j]; }
43 while (x%prime[j]==0) x/=prime[j];
44 }
45 if (x>1) {t[i]++; f[i][t[i]]=x; }
46 for (j=1;j<=t[i];j++) dfs1(i,j,f[i][j]);
47 }
48 ans=0;
49 for (i=1;i<=n;i++)
50 {
51 x=y=0;
52 for (j=1;j<=t[i];j++) dfs2(i,j,1,f[i][j]);
53 if (a[i]==1) x=0; else x--;
54 y=n-1-x;
55 ans=ans+(long long)x*(long long)y;
56 //printf("%d %d %d\n",x,y,ans);
57 }
58 ans=(long long)n*(long long)(n-1)*(long long)(n-2)/6-ans/2;
59 printf("%I64d\n",ans);
60 }
61 }
http://acm.hdu.edu.cn/showproblem.php?pid=5072
