#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
using namespace std;

vector<pair<long long, long long> > indices; 
long long arr[200000];
int main()
{
    int t;
    cin>>t;
    for(int i =0; i<t; i++)
    {
        int n;
        cin>>n;
        long long maximum = -1, minimum = 1e9 + 1;
        indices.clear();
        for(int j = 0; j<n; j++)
        {
            cin>>arr[j];
            maximum = max(maximum, arr[j]);
            minimum = min(minimum, arr[j]);
            indices.push_back(make_pair(arr[j], j));
        }
        if(maximum-minimum == 0)
        {
            cout<<0<<endl;
            continue;
        }
        sort(indices.begin(), indices.end());
        multiset <long long> x, y;
        for(int i = 0; i< n; i++)
        {
            x.insert(arr[i]);
        }
        long long ans = 1e9+1;
        long long left = indices[0].second, right = indices[0].second;
        y.insert(indices[0].first);
        x.erase(x.find(indices[0].first));
        for(int j = 0; j<n ; j++)
        {
            long long new_index = indices[j].second;
            //cout<<j<<" "<<new_index<<" "<<left<<" "<<right<<endl;

            if(new_index > right)
            {
                for(int t = right +1; t<=new_index; t++)
                {
                    y.insert(arr[t]);
                    x.erase(x.find(arr[t]));
                }
                right = new_index;
            }
            if(new_index < left)
            {
                for(int t = left -1; t>=new_index; t--)
                {
                    y.insert(arr[t]);
                    x.erase(x.find(arr[t]));
                }
                left = new_index;
            }
            auto f = x.end();
            f--;
            long long curr_x_maximum = *f;
            long long curr_x_minimum = *x.begin();
            auto z = y.end();
            z--;
            long long curr_y_maximum = *z;
            long long curr_y_minimum = *y.begin();
            long long diff = curr_x_maximum - curr_y_maximum;
            curr_y_minimum += diff;
            ans = min(ans, curr_x_maximum - min(curr_y_minimum, curr_x_minimum));

        }
        x.clear();
        y.clear();
        for(int i = 0; i< n; i++)
        {
            x.insert(arr[i]);
        }
        left = indices[n-1].second;
        right = indices[n-1].second;
        y.insert(indices[n-1].first);
        x.erase(x.find(indices[n-1].first));
        for(int j = n-1; j>=0 ; j--)
        {
            long long new_index = indices[j].second;
            //cout<<j<<" "<<new_index<<" "<<left<<" "<<right<<endl;

            if(new_index > right)
            {
                for(int t = right +1; t<=new_index; t++)
                {
                    y.insert(arr[t]);
                    x.erase(x.find(arr[t]));
                }
                right = new_index;
            }
            if(new_index < left)
            {
                for(int t = left -1; t>=new_index; t--)
                {
                    y.insert(arr[t]);
                    x.erase(x.find(arr[t]));
                }
                left = new_index;
            }
            auto f = x.end();
            f--;
            long long curr_x_maximum = *f;
            long long curr_x_minimum = *x.begin();
            auto z = y.end();
            z--;
            long long curr_y_maximum = *z;
            long long curr_y_minimum = *y.begin();
            long long diff = curr_y_minimum - curr_x_minimum;
            curr_y_maximum -= diff;
            ans = min(ans, max(curr_y_maximum, curr_x_maximum) - curr_x_minimum);

        }
        cout<<ans<<endl;

    }
}