1175C - Electrification - CodeForces Solution

#include<bits/stdc++.h>
#define el '\n'
#define ll long long
#define reset(v, d) memset(v, d , sizeof(v))
#define all(s)  s.begin(), s.end()
#define cin(v)  for(auto &i:v)cin>>i
#define cout(v) for(auto i:v)cout<<i<<" "
using namespace std;
void judge();
const int mod = 1e9 + 7, OO = 2 * 1e9;
const double pi = 3.1415926535897932384;
void solve(){
        int n, k; cin>>n>>k;
        pair<int, int> ans={mod, -1};// pair[dk, x]
        vector<int> a(n);cin(a);
        sort(all(a));
        for(int i=0;i<n-k;i++){
            int x=a[i+k]-a[i];
            ans=min(ans, make_pair(x, a[i]+x/2));
        }
        cout<<ans.second;
}
int main() {
    judge();
    int t=1;
    cin>>t;
    while(t--){
        solve();
        cout<<el;
    }

    return 0;
}

void judge() {
    ios::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(0);
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    freopen("error.txt", "w", stderr);
#endif
}