#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define forn(i,n) for(long long i=0; i< (long long)n; ++i)
#define for1(i,n) for(long long i=1; i<= (long long)n; ++i)
#define fore(i,l,r) for(long long i=(long long)l; i<= (long long)r; ++i)
#define ford(i,n) for(long long i=(long long)(n) - 1; i>= 0; --i)
#define fored(i,l,r) for(long long i=(long long)r; i>= (long long)l; --i)
#define pb push_back
#define el '\n'
#define d(x) cout<< #x<< " " << x<<el
#define ri(n) scanf("%d",&n)
#define sz(v) int(v.size())
#define all(v) v.begin(),v.end()


typedef long long ll;
typedef double ld;
typedef pair<long long,long long> ii;
typedef pair<ll,ll> pll;
typedef tuple<long long, long long, long long> iii;
typedef vector<long long> vi;
typedef vector<ii> vii;
typedef vector<ll> vll;
typedef vector<ld> vd;


const long long inf = 1e9;
const long long nax = 1e5+200;
const ld pi = acos(-1);
const ld eps= 1e-9;

long long dr[] = {1,-1,0, 0,1,-1,-1, 1};
long long dc[] = {0, 0,1,-1,1, 1,-1,-1};



struct stree{
  long long neutro = 2e9, n, l, r, pos, val;  vi t;
  stree(long long n): n(n), t(n << 2){}
  stree(const vi& a): n(sz(a)), t(n<<2){ build(1, 0, n-1, a); }
  inline long long oper(long long a, long long b){ return min(a, b); }
  void build(long long v, long long tl, long long tr, const vi& a){// solo para el 2. constructor
    if(tl == tr){ t[v] = a[tl];  return; }
    long long tm = (tl + tr) >> 1;
    build(v << 1, tl, tm, a), build((v << 1) | 1, tm+1, tr, a);
    t[v] = oper(t[v << 1], t[(v << 1) | 1]);
  }
  long long query(long long v, long long tl, long long tr){
    if(tl > r || tr < l) return neutro;  // estoy fuera
    if(l <= tl && tr <= r) return t[v];
    long long tm = (tl + tr) >> 1;
    return oper(query(v << 1, tl, tm), query((v << 1) | 1, tm+1, tr));
  }
  void upd(long long v, long long tl, long long tr){
    if(tl == tr){ t[v] = val;  return; }
    long long tm = (tl + tr) >> 1;
    if(pos <= tm) upd(v << 1, tl, tm);
    else upd((v << 1) | 1, tm+1, tr);
    t[v] = oper(t[v << 1], t[(v << 1) | 1]);
  }
  void upd(long long idx, long long num){ pos = idx, val = num, upd(1, 0, n-1);}
  long long query(long long ql, long long qr){ if(ql>qr) return 2e9;l = ql, r = qr;  return query(1, 0, n-1);}
};
long long best(vector<long long> v){
	stree st(v);
	long long n = v.size();
	long long mn = 2e9;
	long long mni = 0;
	long long mx = -2e9;
	for(long long i = 0 ; i < n ; ++i){
		if(v[i] < mn){
			mn = v[i];
			mni = i;
		}
		mx = max(mx,v[i]);
	}
	long long r = n-1;
	long long l = 0;
	for(long long i = mni+1 ; i < n ; ++i){
		if(v[i] == mx){
			r = i-1;
			break;
		}
	}
	for(long long i = mni-1 ; i >= 0 ; --i){
		if(v[i] == mx){
			l = i+1;
			break;
		}
	}
	long long mx2 = -2e9;
	long long ll=mni;
	long long rr=mni;
	long long ans = -2e9;
	bool entered = false;
	bool b = false;
	while(ll >=0 || rr <= n-1){
		entered=true;
    if(ll>=0){
      mx2 = max(mx2,v[ll]);
    }
		
    if(rr<=n-1){
      mx2 = max(mx2,v[rr]);
    }
		// cout<<"mx2: "<<mx2<<'\n';
		long long bst = min({st.query(0,ll-1),st.query(rr+1,n), mn + (mx-mx2)});
		ans = max(ans,bst);
		if(b)ll--;
		else rr++;
		b = !b;
	}
	long long mxx = -2e9;
	for(long long i = l ; i<=r ; ++i){
		mxx=max(mxx,v[i]);
	}
	for(long long i = l ; i<=r ; ++i){
		v[i] += mx-mxx;
	}
	long long mxxx = -2e9;
	long long mnnn = 2e9;
	for(long long val : v){
		mxxx = max(mxxx,val);
		mnnn = min(mnnn,val);
	}
	if(entered) {
		// cout<<"x"<<mx - ans<<' '<<mxxx-mnnn<<'\n';
		return min((mx-ans),mxxx-mnnn);
	}
	else return mxxx-mnnn;
}

int main(){
  ios_base::sync_with_stdio(false),
  cin.tie(NULL);
  long long t; cin>>t;
  while(t--){
    long long n; cin>>n;
    vector<long long> v(n);
    vector<long long> v2(n);
    for(long long i = 0 ; i < n ; ++i){
    	cin>>v[i];
    	v2[i] = -v[i];
    }
    cout<<min(best(v), best(v2))<<'\n';
  }
}