Code : Expected Power

#include <atcoder/modint>
#include <bits/stdc++.h>

using namespace std;
using namespace atcoder;
using mint = modint1000000007;

int mx = 1024;

void solve(vector<int> &a, vector<int> &p) {
    int n = a.size();

    vector<mint> dp(mx);
    dp[0] = 1;
    // dp[i] is probability to achieve a xor i.

    for (int i = 0; i < n; i++) {
        mint px = p[i] / (mint)10000;
        vector<mint> ndp(mx);
        for (int old = 0; old < mx; old++) {
            int nxt = old ^ a[i];
            ndp[old] += (1 - px) * dp[old];
            ndp[nxt] += px * dp[old];
        }
        swap(dp, ndp);
    }
    mint ans = 0;
    for (int x = 0; x < mx; x++) {
        ans += 1LL * x * x * dp[x];
    }

    cout << ans.val() << "\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int t;
    cin >> t;
    for (int zz = 0; zz < t; zz++) {
        int n;
        cin >> n;
        vector<int> a(n), p(n);
        for (int i = 0; i < n; i++) {
            cin >> a[i];
        }
        for (int i = 0; i < n; i++) {
            cin >> p[i];
        }

        solve(a, p);
    }
}