发第 4 遍了，真的找不出错来 UwU

#include <iostream>
#include <vector>
#define oddc (color[i] << 1 | 1)
#define evenc (color[i] << 1)
using namespace std;
const int MOD = 10007;
const int S = 1e5 + 5;
typedef long long LL;
int n, m;
LL ans;
LL number[S], color[S];
LL sum[2 * S];
vector<LL> e[2 * S]; 
int main() {
	cin >> n >> m;
	for (int i = 1; i <= n; i++) {
		cin >> number[i];
	}
	for (int i = 1; i <= n; i++) {
		cin >> color[i];
	}
	for (int i = 1; i <= n; i++) {
		if (i & 1) {
			e[oddc].push_back(i);
			sum[oddc] = (sum[oddc] + number[i]) % MOD;
		} else {
			e[evenc].push_back(i);
			sum[evenc] = (sum[evenc] + number[i]) % MOD;
		}
	}
	for (int i = 2; i <= (m << 1 | 1); i++) {
		if (e[i].size() > 1) {
			for (int j = 0; j < e[i].size(); j++) {
				LL idx = e[i][j] % MOD;
				LL nsum = (sum[i] + ((e[i].size() - 2) * number[idx]) % MOD) % MOD;
				ans = (ans + idx * nsum % MOD) % MOD;
			}
		}
	}
	cout << ans;
	return 0;
}