1 // luogu-judger-enable-o2
 2 #include<iostream>
 3 #include<cstdio>
 4 #include<cstring>
 5 #include<algorithm>
 6 #include<cctype>
 7 #include<vector>
 8 using namespace std;
 9 vector<int>a[10001];//每个种类的集合（各元素下标）
10 int ans;char ch;
11 const long long P=10007;
12 int b[100001],zh[100001],bi[100001];//营养、种类、种类里的下标
13 int nxt[100001];//下一个
14 int reans;
15 inline int read()
16 {
17     ans=0;
18     ch=getchar();
19     while(!isdigit(ch)) ch=getchar();
20     while(isdigit(ch)) ans=(ans<<3)+(ans<<1)+ch-'0',ch=getchar();
21     return ans;
22 }
23 int w;
24 int main()
25 {
26 //    freopen("data1.in.txt","r",stdin);
27     int n=read(),m=read();
28     for(register int i=1;i<=n;i++)
29         b[i]=read();
30     for(register int i=1;i<=n;i++)
31     {
32         zh[i]=read();
33         a[zh[i]].push_back(i);
34         bi[i]=a[zh[i]].size()-1;
35         for(int j=bi[i]-1;j>=0;j--)
36         {
37             if((i-a[zh[i]][j])%3==0)
38                 {
39                     nxt[a[zh[i]][j]]=i;
40                     break;
41                 }
42         }
43     }
44     int y;
45     long long an;
46     for(int i=1;i<=n;i++)
47     {
48         for(int j=nxt[i];j<=n&&j;j=nxt[j])
49         {
50             an=(i+j)*(long long)(b[i]-b[j]);
51             reans=(reans+an)%P;
52         }
53     }
54     if(reans<0) reans+=P;
55     printf("%d",reans);
56     return 0;
57 }

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<cstring>
 4 #include<cctype>
 5 #include<ctime>
 6 using namespace std;
 7 const int mod=10007;
 8 int sx[100001],sbx[100001],sxbx[100001],s[100001],a[100001],b[100001];
 9 int ans;
10 char ch;
11 inline int read()
12 {
13     ans=0;
14     ch=getchar();
15     while(!isdigit(ch)) ch=getchar();
16     while(isdigit(ch)) ans=(ans<<3)+(ans<<1)+ch-'0',ch=getchar();
17     return ans;
18 }
19 int main()
20 {
21     int n;
22     n=read();read();//m其实并没用
23     for(int i=1;i<=n;i++) b[i]=read()%mod;
24     for(int i=1;i<=n;i++) a[i]=read();
25     ans=0;
26     for(int gro=1;gro<=3;gro++)//差三的倍数的分一组，共有三组：%3=0的；%3=1的和%3=2的。
27     {
28         memset(sx,0,sizeof sx);
29         memset(sbx,0,sizeof sbx);
30         memset(sxbx,0,sizeof sxbx);
31         memset(s,0,sizeof s);
32         for(int z=gro;z<=n;z+=3)
33         {
34             ans=(ans+sxbx[a[z]])%mod;
35             ans=(ans-b[z]*sx[a[z]]%mod)%mod;
36             ans=(ans+z*sbx[a[z]])%mod;
37             ans=(ans-z*b[z]%mod*s[a[z]])%mod;
38             sxbx[a[z]]=(sxbx[a[z]]+z*b[z]%mod)%mod;
39             sx[a[z]]=(sx[a[z]]+z)%mod;
40             s[a[z]]=(s[a[z]]+1)%mod;
41             sbx[a[z]]=(sbx[a[z]]+b[z])%mod;
42         }
43     }
44     if(ans<0) ans+=mod;
45     printf("%d",ans);
46     return 0;
47 }