average x y if ge x y x y if true x y averIter y x y if false x y averIter x y x averIter x y z ifIter ge x y x y z ifIter true x y z z ifIter false x y z averIter plus x s s s 0 plus y s 0 plus z s 0 append nil y y append cons n x y cons n app x y low n nil nil low n cons m x if_low ge m n n cons m x if_low false n cons m x cons m low n x if_low true n cons m x low n x high n nil nil high n cons m x if_high ge m n n cons m x if_high false n cons m x high n x if_high true n cons m x cons average m m high n x quicksort x ifquick isempty x x ifquick true x nil ifquick false x append quicksort low head x tail x cons tail x quicksort high head x tail x plus 0 y y plus s x y s plus x y isempty nil true isempty cons n x false head nil error head cons n x n tail nil nil tail cons n x x ge x 0 true ge 0 s y false ge s x s y ge x y a b a c 2.2 ifIter false x y z averIter plus x s s s 0 plus y s 0 plus z s 0 average x y if ge x y x y if_low false n cons m x low n x quicksort x ifquick isempty x x high n cons m x ge m n low n cons m x if_low ge m n n cons m x ifquick false x tail x ifquick false x head x low n cons m x ge m n if_high false n cons m x high n x quicksort x isempty x average x y ge x y plus s x y plus x y ifquick false x tail x if_low true n cons m x low n x ge s x s y ge x y averIter x y z ge x y ifIter false x y z plus z s 0 if false x y averIter x y x ifquick false x high head x tail x if_high true n cons m x high n x ifquick false x low head x tail x averIter x y z ifIter ge x y x y z ifquick false x tail x if_high true n cons m x average m m ifquick false x quicksort high head x tail x ifquick false x quicksort low head x tail x ifIter false x y z plus x s s s 0 if true x y averIter y x y high n cons m x if_high ge m n n cons m x ifquick false x append quicksort low head x tail x cons tail x quicksort high head x tail x ifIter false x y z plus y s 0 ifquick false x head x true ifquick false x quicksort low head x tail x ifquick false x quicksort high head x tail x quicksort x ifquick isempty x x true Failed! NaTT certifiable-1.6