【NOIP2015】求和

#include
#include
using namespace std;
int main(){
    int n,m,cor;
    long sum=0;
    scanf("%d%d",&n,&m);
    long color[m+1][3][2],number[n+1],count[m+1][2];
    memset(count,0,sizeof(count));
    memset(color,0,sizeof(color));
    for(int i=1;i<=n;i++)
        scanf("%ld",&number[i]);
    for(int i=1;i<=n;i++){
        scanf("%d",&cor);
        color[cor][0][i&1]+=i;
        color[cor][1][i&1]+=number[i];
        color[cor][2][i&1]+=number[i]*i;
        count[cor][i&1]++;
    }
    for(int i=1;i<=m;i++)
        for(int j=0;j<=1;j++)
            sum+=color[i][0][j]*color[i][1][j]+(count[i][j]-2)*color[i][2][j];
            sum%=10007;
    printf("%d",sum);
    return 0;
}