照顾新手(梅开二度)

#include<bits/stdc++.h>
using namespace std;
const int mod=10007;
const int maxn=1e5+10;
int n,m;
int a[maxn],b[maxn];
int s1[maxn][2],s2[maxn][2];
int ans;
int main(){
    cin>>n>>m;
    for(int i=1;i<=n;i++)
        cin>>a[i];
    for(int i=1;i<=n;i++){
        cin>>b[i]; 
        s1[b[i]][i%2]++;
        s2[b[i]][i%2]=(s2[b[i]][i%2]+a[i])%mod;
    }    
    for(int i=1;i<=n;i++){
        int y=b[i];
        ans+=i*(s2[y][i%2]+a[i]*(s1[y][i%2]-2)%mod)%mod;
        ans%=mod;
    }
    cout<<ans<<endl;
    return 0;
}