[CSES] Book Shop

void solve()
{
    ll n, x;
    cin >> n >> x;

    vll cost(n), p(n);
    rep(i, n) cin >> cost[i];
    rep(i, n) cin >> p[i];

    vll A(x + 1, 0LL), B(x + 1, 0LL);
    rep(i, n)
    {
        rep(j, x + 1)
        {
            A[j] = B[j];
            if (j - cost[i] >= 0)
                A[j] = max(A[j], B[j - cost[i]] + p[i]);
        }
        rep(j, x + 1) B[j] = A[j], A[j] = 0;
    }

    ll ans = 0LL;
    rep(i, x + 1) ans = max(ans, B[i]);

    cout << ans << "\n";
}