#include<bits/stdc++.h>
using namespace std;
#define For(i,a,b) for(int i=a;i<=(b);i++)
#define Rof(i,a,b) for(int i=a;i>=(b);i--)
#define FOR(i,a) for(int i=0;i<a;i++)
#define clr(a) memset(a,0,sizeof(a))
#define wln putchar('\n')
#define lwb lower_bound
#define upb upper_bound
#define pb push_back
#define mp make_pair
#define rng(a) a.begin(),a.end()
typedef unsigned long long ull;
typedef double db;
typedef long double ld;
typedef vector<int> vi;
typedef long long ll;
typedef unsigned ui;
typedef pair<int,int> pii;
template<class T1,class T2> void chkmin(T1 &x,T2 y){if(y<x)x=y;}
template<class T1,class T2> void chkmax(T1 &x,T2 y){if(y>x)x=y;}
const int BUF_SIZE=1<<20;
char buf[BUF_SIZE],*P1=buf,*P2=buf,obuf[BUF_SIZE],*PO=obuf;
char getc()
{
    if(P1==P2)P2=(P1=buf)+fread(buf,1,BUF_SIZE,stdin);
    return P1==P2?EOF:*P1++;
}
void read(int &x)
{
    char ch=getc(); x=0;
    while(!isdigit(ch))ch=getc();
    while(isdigit(ch))x=x*10+(ch^48),ch=getc();
}
void flushO()
{
    fwrite(obuf,PO-obuf,1,stdout);
    PO=obuf;
}
void putc(char ch)
{
    if(PO==obuf+(BUF_SIZE))flushO();
    *PO++=ch;
}
void prints(char s[]){for(char* ss=s;*ss!='\0';ss++)putc(*ss);}
void write(ll x)
{
    if(x>9)write(x/10);
    putc(x%10^48);
}
const int N=100005,INF=1000000007;
const ll INFll=1ll*INF*INF;
int n,a[N];
struct segtree
{
    struct node{ll v[2][2];}v[N<<2];
    friend node operator +(node a,node b)
    {
        node c;
        For(i,0,1)
            For(j,0,1)
            {
                c.v[i][j]=min(max(a.v[i][0],b.v[0][j]),max(a.v[i][1],b.v[1][j]));
                //printf("%lld %lld %lld %lld %lld\n",c.v[i][j],a.v[i][0],b.v[0][j],a.v[i][1],b.v[1][j]);
            }
        return c;
    }
    void pushup(int id){v[id]=v[id<<1]+v[id<<1|1];}
    void build(int id,int l,int r)
    {
        if(l==r)
        {
            v[id]={a[l],a[l]+a[l+1],-INFll,INFll};
            return;
        }
        int mid=l+r>>1;
        build(id<<1,l,mid);
        build(id<<1|1,mid+1,r);
        pushup(id);
        //printf("(%d,%d):v[%d]={%lld,%lld,%lld,%lld}\n",l,r,id,v[id].v[0][0],v[id].v[0][1],v[id].v[1][0],v[id].v[1][1]);
    }
    void modify(int id,int l,int r,int x,int y)
    {
        if(l==r)
        {
            v[id].v[0][y]=INFll;
            return;
        }
        int mid=l+r>>1;
        if(x<=mid)modify(id<<1,l,mid,x,y);
        else modify(id<<1|1,mid+1,r,x,y);
        pushup(id);
    }
}T;
typedef tuple<int,int,int> piii;
piii o[N<<1];
void Main()
{
    scanf("%d",&n);
    For(i,1,n)scanf("%d",a+i),o[i]={a[i],i,0};
    For(i,1,n-1)o[n+i]={a[i]+a[i+1],i,1};
    sort(o+1,o+n+n);
    T.build(1,1,n);
    ll ans=INFll;
    For(i,1,n*2-1)
    {
        //printf("%lld %d\n",T.v[1].v[0][0],get<0>(o[i]));
        chkmin(ans,T.v[1].v[0][0]-get<0>(o[i]));
        T.modify(1,1,n,get<1>(o[i]),get<2>(o[i]));
    }
    printf("%lld\n",ans);
}
int main()
{
    //freopen("out.txt","w",stdout);
    int t;
    scanf("%d",&t);
    while(t--)Main();
}