#include<bits/stdc++.h>
#define ls(x) (x<<1)
#define rs(x) (x<<1|1)
using namespace std;
constexpr int M=1e5+5;
vector<pair<int,int>>pos[M<<1];
int n,m,ans,num,a[M],lsh[M<<1];
struct matrix{bool mat00,mat01,mat10,mat11;}tr[M<<2];
matrix operator * (matrix a,matrix b){
	return {a.mat00&&b.mat00||a.mat01&&b.mat10,a.mat00&&b.mat01||a.mat01&&b.mat11,
			a.mat10&&b.mat00||a.mat11&&b.mat10,a.mat10&&b.mat01||a.mat11&&b.mat11};
}
int read(){
	int x=0,f=1;char ch=getchar();
	while (!isdigit(ch)) {if (ch=='-') f=-1;ch=getchar();}
	while (isdigit(ch)) x=x*10+ch-48,ch=getchar();
	return x*f;
}
void build(int l,int r,int x){
	tr[x].mat00=tr[x].mat01=tr[x].mat10=tr[x].mat11=0;
	if (l==r) return tr[x].mat10=1,void();int mid=l+r>>1;
	build(l,mid,ls(x));build(mid+1,r,rs(x));tr[x]=tr[ls(x)]*tr[rs(x)];
}
void update(int u,int c,int l=1,int r=n,int x=1){
	if (l==r){
		if (!c) tr[x].mat00^=1;
		else if (c==1) tr[x].mat01^=1;
		else tr[x].mat11^=1;
		return ;
	}
	int mid=l+r>>1;
	if (u<=mid) update(u,c,l,mid,ls(x));
	else update(u,c,mid+1,r,rs(x));
	tr[x]=tr[ls(x)]*tr[rs(x)];
}
void modify(int now){
	for (auto [x,y]:pos[now])
		if (y) update(x,1);
		else {
			update(x,2);
			if (x<n) update(x+1,0);
		}
}
void solve(){
	n=read();num=0;
	for (int i=1;i<=n;i++){
		a[i]=read();lsh[++num]=a[i];
		if (i>1) lsh[++num]=a[i-1]+a[i];
	}
	sort(lsh+1,lsh+num+1);num=unique(lsh+1,lsh+num+1)-lsh-1;
	for (int i=1;i<=num;i++) pos[i].clear();
	for (int i=1;i<=n;i++){
		pos[lower_bound(lsh+1,lsh+num+1,a[i])-lsh].push_back({i,0});
		if (i>1) pos[lower_bound(lsh+1,lsh+num+1,a[i-1]+a[i])-lsh].push_back({i,1});
	} ans=INT_MAX;build(1,n,1);
	for (int l=1,r=1;r<=num;r++){
		modify(r);
		while (tr[1].mat11&&l<=r){
			ans=min(ans,lsh[r]-lsh[l]);
			modify(l++);
		}
	}
	printf("%d\n",ans);
}
int main(){int T=read();
	while (T--) solve();
	return 0;
}