如何优化？

#include <bits/stdc++.h>
#define ll long long
using namespace std;
int n,x,y,m;
int c[200000],num[200000];
ll ans;
signed main() {
	ios_base::sync_with_stdio(false)；
    cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>num[i];
	}
	for(int i=1;i<=n;i++){
		cin>>c[i];
	}
//	for(int i=1;i<=n;i++)cout<<c[i]<<" ";
//	cout<<endl;
	for(int x=1;x<=n/2;x++){
		for(int z=n;z>x;z--){
			if(c[x]!=c[z])continue;
			int y=(z+x)/2;
			if(z-y!=y-x)continue;
			if(y<=x||y>=z)continue;
			if(x>=z)continue;
			ans+=(x+z)*(num[x]+num[z]);
			ans%=10007;
//			cout<<x<<" "<<y<<" "<<z<<endl;
		}
	}
	cout<<ans<<endl;
    return 0;
}