#include <iostream>
using namespace std;
int a[100005];
long long qp(long long n, long long m, long long p) {
    long long ans = 1, base = n;
    while (m) {
        if (m & 1) (ans *= base) %= p;
        (base *= base) %= p; m >>= 1;
    }
    return ans;
}
int main() {
    long long n, k, sa=0, sb=0, sp3=0, t; cin >> n >> k;
    for (int i=1; i<=n; i++) {cin >> a[i]; (sa += a[i]) %= 998244353;}
    for (int i=1; i<=n; i++) {cin >> t; (sb += t) %= 998244353; (sp3 += (a[i] * t) % 998244353) %= 998244353;}
    if (k == 0) {cout << n; return 0;}
    cout << ((sa * sb + 998244353) % 998244353 * qp(sp3, k-1, 998244353)) % 998244353;
    return 0;
}

完了，结论题代码不会写了

感觉怎么着都不至于出负数吧