#include<bits/stdc++.h>

 using namespace std;

 typedef long long ll;

 typedef unsigned int uint;

 typedef unsigned long long ull;

 typedef pair<int,int> PII;

 typedef pair<ll,ll> Pll;

 typedef vector<int> VI;

 typedef vector<PII> VII;

 typedef pair<ll,ll>P;

 #define N  400010

 #define M  200010

 #define fi first

 #define se second

 #define MP make_pair

 #define pi acos(-1)

 #define mem(a,b) memset(a,b,sizeof(a))

 #define rep(i,a,b) for(int i=(int)a;i<=(int)b;i++)

 #define per(i,a,b) for(int i=(int)a;i>=(int)b;i--)

 #define lowbit(x) x&(-x)

 #define Rand (rand()*(1<<16)+rand())

 #define id(x) ((x)<=B?(x):m-n/(x)+1)

 #define ls p<<1

 #define rs p<<1|1

 const ll MOD=1e9+,inv2=(MOD+)/;

       double eps=1e-;

       ll INF=1e10;

       ll inf=5e13;

       int dx[]={-,,,};

       int dy[]={,,-,};

 map<ll,int> mp;

 int t[N],n,k,id;

 ll s[M],a[M],b[M],c[N];

 int read()

 {

    int v=,f=;

    char c=getchar();

    while(c<||<c) {if(c=='-') f=-; c=getchar();}

    while(<=c&&c<=) v=(v<<)+v+v+c-,c=getchar();

    return v*f;

 }

 void update(int x,int y)

 {

     while(x)

     {

         t[x]=max(t[x],y);

         x-=lowbit(x);

     }

 }

 int query(int x)

 {

     int res=-2e6;

     while(x<=id)

     {

         res=max(res,t[x]);

         x+=lowbit(x);

     }

     return res;

 }

 int isok(ll mid)

 {

     mp.clear();

     int m=;

     rep(i,,n+) b[i]=a[i]-mid;

     int i=,j=;

     while(i<=n+&&j<=n+)

     {

         m++;

         if(a[i]<b[j])

         {

             c[m]=a[i];

             i++;

         }

          else

          {

              c[m]=b[j];

              j++;

          }

     }

     while(i<=n+)

     {

         c[++m]=a[i];

         i++;

     }

     while(j<=n+)

     {

         c[++m]=b[j];

         j++;

     }

     id=;

     mp[c[]]=;

     rep(i,,m)

      if(c[i]!=c[i-]) mp[c[i]]=++id;

     rep(i,,id) t[i]=-2e6;

     update(mp[],);

     int ans=,flag=;

     rep(i,,n)

     {

         int tmp=query(mp[s[i]-mid]);

         ans=max(ans,tmp+);

         if(ans>=k) return ;

         update(mp[s[i]],tmp+);

     }

     return ;

 }

 int main()

 {

     int cas=read();

     while(cas--)

     {

         n=read(),k=read();

         s[]=;

         rep(i,,n)

         {

             int x=read();

             s[i]=s[i-]+x;

         }

         rep(i,,n+) a[i]=s[i-];

         sort(a+,a+n++);

         ll l=-1e10,r=1e10,last=1e10;

         while(l<=r)

         {

             ll mid=(l+r)>>;

             if(isok(mid)){last=mid; r=mid-;}

              else l=mid+;

         }

         printf("%I64d\n",last);

     }

     return ;

 }