#include<bits/stdc++.h>
#define ll int
#define pb push_back
#define N 200000
#define pll pair<ll,ll>
#define pcl pair<char,ll>
#define x first
#define y second
#define tll tuple<ll,ll,ll>
#define MOD 1000000007
#define inf 2000000000000001ll
#define m_p make_pair
#define pxm pair<ll,map<ll,ll> *>

using namespace std;
//shb


ll n;
ll num[N],mx[2*N][__lg(N)+2],mn[2*N][__lg(N)+2];

ll find_max(ll lt,ll rt)
{
    ll len=rt-lt+1;
    ll k=__lg(len);
    return max(mx[lt][k],mx[rt-(1<<k)+1][k]);
}

ll find_min(ll lt,ll rt)
{
    ll len=rt-lt+1;
    ll k=__lg(len);
    return min(mn[lt][k],mn[rt-(1<<k)+1][k]);
}


ll counter_clockwise(ll lt,ll rt)   //lt--->rt
{
    if(rt<lt)
    {
        rt+=n;
        // swap(lt,rt);
    }
    // cout<<lt<<" "<<rt<<"\n";
    return find_max(lt,rt)-find_min(lt,rt);
}


void solve()
{
    cin>>n;
    for(ll i=0;i<n;i++)
    {
        cin>>num[i];
        mx[i+n][0]=mx[i][0]=
        mn[i+n][0]=mn[i][0]=num[i];
    }
    
    for(ll j=1;j<=__lg(2*n);j++)for(ll i=0;(i+(1<j))<=2*n;i++)
    {
        mx[i][j]=max(mx[i][j-1],mx[i+(1<<(j-1))][j-1]);
        mn[i][j]=min(mn[i][j-1],mn[i+(1<<(j-1))][j-1]);
    }
    ll ans=find_max(0,n-1)-find_min(0,n-1);
    for(ll i=0;i<n;i++)
    {
        ll j=i;
        for(ll x=n-1;x>=1;x/=2)
        {
            while((j+x)<(i+n-1) && counter_clockwise(i,(j+x)%n) <= counter_clockwise((j+x+1)%n,(i-1+n)%n))
                j+=x;
        }
        // cout<<i<<" "<<j<<"\n";
        ans=min(ans,max(counter_clockwise(i,j%n),
        counter_clockwise((j+1)%n,(i-1+n)%n)));
    }
    // cout<<counter_clockwise(3,0)<<"\n";
    cout<<ans<<"\n";


}



int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    // init();
    ll t=1;
    cin>>t;
    // cout<<__lg(1ll<<62)<<endl;
    ll a,b,c,d;
    for(ll i=1;i<=t;i++)
    {
        // cout<<"Case "<<i<<": ";
        solve();
    }
}