STL

/// policy based data structures 

#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp>
#include <functional> // for less
#include <iostream>
#define   MP             make_pair
#define   PB             push_back
#define   nn             '\n'
#define   endl           '\n'
#define   IOS            ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define   UNIQUE(vec)    vec.resize(distance(vec.begin(),unique(vec.begin(),vec.end()))) ;
#define   all(vec)       vec.begin(),vec.end()
#define   int            long long
#define   pii            pair<int,int>
#define   pdd            pair<double,double>
using namespace __gnu_pbds;
using namespace std ;

typedef long long LL ;

const int MOD=1e9+7,Base=998244353 ;
const int N=1e6+7 ;
const int oo=1LL*1000*1000*1000*1000*1000*1000+7LL ;
const double pie=acos(-1.0) ;
const double EPS=1e-9 ;

int test, n, a[N], k ;

/*
typedef tree<int, null_type,  less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_multiset;
ordered_multiset omset ;
int value = *omset.find_by_order(k) ;
omset.erase(omset.find_by_order(omset.order_of_key(value))) ;
/**/


int32_t main()
{
    IOS

    cin>>test ;

    while(test--)
    {
        cin>>n>>k ;

        ordered_multiset omset ;

        omset.insert(oo) ;
        omset.insert(oo) ;
        omset.insert(oo) ;
        omset.insert(oo) ;

        for(int i=1; i<=n; ++i)
        {
            cin>>a[i] ;
            omset.insert(a[i]) ;
        }

        int ans=-oo ;

        for(int i=1; i<n; ++i)
        {
            int Min = min(a[i],a[i+1]), Max = max(a[i],a[i+1]), vk ;

            omset.erase(omset.find_by_order(omset.order_of_key(Min))) ;

            omset.erase(omset.find_by_order(omset.order_of_key(Max))) ;

            vk = *omset.find_by_order(k) ;

            ans=max(ans,min(Min,2LL*vk)) ;

            vk = *omset.find_by_order(k-1) ;

            ans=max(ans,min(Max,2LL*vk)) ;

            if(k>=2)
            {
                vk = *omset.find_by_order(max(0LL,k-2)) ;
                ans=max(ans,2LL*vk) ;
            }

            omset.insert(Min) ;

            omset.insert(Max) ;
        }

        ans=min(ans,1LL*1000*1000*1000) ;

        cout<<ans<<endl ;

    }

    /**/

    return 0 ;
}