#include<iostream>
using namespace std;
const int N=2e5+10;
int t,n;
int a[N];
int maxx,minn;
int ans=0;
bool check(int x)   //能否把最大值下降x点距离 
{
	//if(x==0) return 1;
	//cout<<x<<endl; 
	int lj=2e5+10,rj=0;
	//int lb=2e5+10,rb=0;
	for(int i=1;i<=n;i++)
	{
		if(a[i]>maxx-x)     //需要下降 
		{
			rj=max(rj,i);
			lj=min(lj,i);
		}
	}
	for(int i=1;i<=n;i++)
	{
	    if(a[i]<minn+x)     //不能下降 
		{
			if(i>=lj&&i<=rj) return 0;
		}
	}
	return 1;
}
int main()
{
	cin>>t;
	while(t--)
	{
	cin>>n;
	maxx=0,minn=1e9+10;
	for(int i=1;i<=n;i++) 
	{
		cin>>a[i];
		maxx=max(maxx,a[i]);
		minn=min(minn,a[i]);
	}
	int l=0,r=maxx-minn;
	ans=0;
	while(l<=r)
	{
		int mid=(l+r)/2;
		if(check(mid))
		{
			ans=mid;
			l=mid+1;
		}
		else r=mid-1;
	}
	cout<<maxx-minn-ans<<endl;
    }
    return 0;
}