//
// Created by admin on 2023/11/23.
//
#include <bits/stdc++.h>

using namespace std;
int t;
typedef long long ll;
typedef pair<ll, ll> pl;

vector<pl> dp[2]{{},
                 {}};

void solve() {
    int n;
    cin >> n;
    vector<ll> a(n);
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }
    if(n == 1 || n == 2) {
        cout << "0\n";
        return;
    }
    dp[0] = {};
    dp[1] = {};
    dp[0].push_back({a[0], a[0]});
    dp[1].push_back({min(a[0], a[1]), max(a[0], a[1])});
    dp[1].push_back({a[0] + a[1], a[0] + a[1]});
    for (int i = 2; i < n; ++i) {
        vector<pl> tmp{};
        for (int ind = 0; ind < 2; ++ind) {
            ll v = ind == 0 ? (a[i] + a[i - 1]) : a[i];
            for (int j = 0; j < dp[ind].size(); ++j) {
                pl p = dp[ind][j];
                p.first = min(p.first, v);
                p.second = max(p.second, v);
                tmp.push_back(p);
            }
        }
        std::sort(tmp.begin(), tmp.end(),
                  [](pl p1, pl p2) {
                      if(p1.first < p2.first)return true;
                      return p1.second > p2.second;
                  }
        );

        vector<pl> dp_cur{};
        ll r = 1e18;
        for (int j = tmp.size() - 1; j >= 0; --j) {
            if(tmp[j].second >= r) {
                continue;
            }
            dp_cur.push_back(tmp[j]);
            r = tmp[j].second;
        }
        swap(dp[0], dp[1]);
//        dp[0] = dp[1];
        dp[1] = std::move(dp_cur);
    }
    ll ans = 1e12;
    for (auto &i: dp[1]) {
        ll dif = i.second - i.first;
        ans = min(ans, dif);
    }
    cout << ans << '\n';
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << setprecision(10) << fixed;
    cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}