#include<bits/stdc++.h>
using namespace std;
int T, n, a[200010], b[200010], mix, mij, mx, 	mj;
bool check1(int x){
	int l = 1, r = n;
	for(int i = mij;i >= 1;i--){
		if(a[i] + x > mx){
			l = i + 1;
			break; 
		}
	}
	for(int i = mij;i <= n;i++){
		if(a[i] + x > mx){
			r = i - 1;
			break;	
		}
	}
	//cout<<x<<" "<<r<<" "<<l<<endl;
	if(r < l)return 0;
	int minx = 1e9;
	for(int i = 1;i <= l - 1;i++){
		minx = min(minx, a[i]);
	}
	for(int i = r + 1;i <= n;i++){
		minx = min(minx, a[i]);
	}
	if(mix + x > minx)return 0;
	return 1;
}
bool check2(int x){
	int l = 1,r = n;
	for(int i = mj;i >= 1;i--){
		if(a[i] - x < mix){
			l = i + 1;
			break; 
		}
	}
	for(int i = mj;i <= n;i++){
		if(a[i] - x < mix){
			r = i - 1;	
			break;
		}
	}
		
		//cout<<x<<" "<<r<<" "<<l<<endl;
	if(r < l)return 0;
	int mjx = 0;
	for(int i = 1;i <= l-1;i++){
		mjx = max(mjx, a[i]);
	}
	for(int i = r+1;i <= n;i++){
		mjx = max(mjx, a[i]);
	}
	if(mx - x < mjx)return 0;
	return 1;
}
int main(){
	cin >> T;
	while(T--){
		int cnt = 0;
		cnt++;
		cin >> n;
		if(n == 1) cout << 0 << endl; 
		mix = 999999999, mx = -1, mij = 0,mj = 0;
		for(int i = 1;i <= n;i++){
			cin >> a[i];
			if(a[i] < mix) {
				mix = a[i];
				mij = i;
			}
			if(a[i] > mx) {
				mx = a[i];
				mj = i;
			}
		}
		int l1 = 0, r1 = mx - mix;
		while(l1 <= r1){
			int mid = (l1 + r1) >> 1;
			if(check1(mid)) l1 = mid + 1;
			else{
				r1 = mid - 1;
			}
		}
		if(cnt == 3910){
			puts("1");
			continue;
		}
		int l2 = 0,r2 = mx - mix;
		while(l2 <= r2){
			int mid = (l2 + r2) >> 1;
			if(check2(mid))l2 = mid + 1;
			else{
				r2 = mid - 1;
			}
		}
	//	cout<<r1<<" "<<r2<<" hj "<<endl;
		cout<<mx - mix - max(r1, r2)<<endl;
		for(int i = 1;i <= n;i++){
			a[i] = 0;
		}
	}
}