Seeking a better solution for Chef and laddus for children

Hello guys, I am looking for an O(n) solution for Chef and Laddus for Children, problem link mine involves sorting and hence O(nlog(n)).

  void Solve(){
      int n,k;
      cin>>n>>k;
      vector<ll>v(n,0);
      for(int i =0;i<n;i++) cin>>v[i];
      SortVector(v);
      ll ans = Mod;
      for(int i = n-1;i>=0;i--) ((i-k+1>=0)?ans = min(ans,v[i]-v[i-k+1]):ans = ans);
      cout<<ans<<'\n';
    }

SortVector() is a macro