Code : Maximum Sum

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

using namespace std;
using namespace atcoder;

using mint = modint1000000007;

#define endl "\n"

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

    vector<long long> dp(n, -1);
    dp[0] = a[0];
    for (int i = 1; i < n; i++) {
        dp[i] = max(a[i], a[i] + dp[i - 1]);
    }

    auto x = max(0LL, *max_element(dp.begin(), dp.end()));
    auto remain = accumulate(a.begin(), a.end(), 0LL) - x;

    mint ans = 0, two = 2;
    ans += two.pow(k) * x;
    ans += remain;

    cout << ans.val() << endl;
}

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

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