diff --git a/app/controllers/main_controller.rb b/app/controllers/main_controller.rb
--- a/app/controllers/main_controller.rb
+++ b/app/controllers/main_controller.rb
@@ -107,7 +107,7 @@
 
   def submission
     @user = User.find(session[:user_id])
-    @problems = Problem.find_available_problems
+    @problems = @user.available_problems
     if params[:id]==nil
       @problem = nil
       @submissions = nil
@@ -193,54 +193,13 @@
     end
   end
 
-  def problem_list_by_user_contests(user)
-    contest_problems = []
-    pin = {}
-    user.contests.enabled.each do |contest|
-      available_problems = contest.problems.available
-      contest_problems << {
-        :contest => contest,
-        :problems => available_problems
-      }
-      available_problems.each {|p| pin[p.id] = true}
-    end
-    other_avaiable_problems = Problem.available.find_all {|p| pin[p.id]==nil and p.contests.length==0}
-    contest_problems << {
-      :contest => nil,
-      :problems => other_avaiable_problems
-    }
-    return contest_problems
-  end
-
-  def problem_list_for_user(user, contest_problems=nil)
-    if not Configuration.multicontests?
-      return Problem.find_available_problems
-    else
-      if contest_problems==nil
-        contest_problems = problem_list_by_user_contests(user)
-      end
-
-      problems = []
-      collected = {}
-      contest_problems.each do |cp|
-        cp[:problems].each do |problem|
-          if not collected[problem.id]
-            problems << problem
-            collected[problem.id] = true
-          end
-        end
-      end
-      return problems
-    end
-  end
-
   def prepare_list_information
     @user = User.find(session[:user_id])
     if not Configuration.multicontests?
       @problems = problem_list_for_user(@user)
     else
-      @contest_problems = problem_list_by_user_contests(@user)
-      @problems = problem_list_for_user(@user, @contest_problems)
+      @contest_problems = @user.available_problems_group_by_contests
+      @problems = @user.available_problems
     end
     @prob_submissions = {}
     @problems.each do |p|