/**
  * 分页显示整个问题目录.
  *
  * @return Response
  */
 public function index(Request $request)
 {
     $subArr = array();
     //提交的题目
     $acArr = array();
     //通过的题目
     if (Auth::check()) {
         $subArr = DB::table('solution')->where('user_id', Auth::user()->user_id)->groupBy('problem_id')->lists('problem_id');
         $acArr = DB::table('solution')->where('user_id', Auth::user()->user_id)->where('result', '4')->groupBy('problem_id')->lists('problem_id');
     }
     $id = $request->input('id');
     $title = $request->input('title');
     $data = Problem::paginate(30);
     if ($id != "") {
         return $this->show($id);
     }
     if ($title != "") {
         $data = Problem::where('title', 'like', '%' . $title . '%')->paginate(30);
         return view('problems.index')->with(['problems' => $data, 'subArr' => $subArr, 'acArr' => $acArr]);
     }
     return view('problems.index')->with(['problems' => $data, 'subArr' => $subArr, 'acArr' => $acArr, 'pageSaved' => 'true']);
 }