nodes
(Anzahl aller inneren Knoten) durch tfold
foo = tfold Leaf ( \ fl k fr -> Node { key = k, left = fr, right = fl } )
contains
,
die Schlüssel in einem Suchbaum wiederfindet.
Benutze tfold
.
contains :: Ord a => a -> Tree a -> Bool -- contains 2 $ suchbaum [ 5,2,6,4,7,4,9 ] ==> True contains x = tfold False ( \ cl k cr -> undefined )