[Update] control range of game

game.cpp

@@ -43,8 +43,8 @@ class Game {
             this->count++;
             if (num == answer) return true;
 
-            if (num > answer) this->upper = num;
-            else if (num < answer) this->lower = num;
+            if (num > answer && num < this->upper) this->upper = num;
+            else if (num < answer && num > this->lower) this->lower = num;
 
             return false;
         }