First BST
root1 = Node_ ( 15 ) NEW_LINE root1 . left = Node_ ( 10 ) NEW_LINE root1 . right = Node_ ( 20 ) NEW_LINE root1 . left . left = Node_ ( 5 ) NEW_LINE root1 . left . right = Node_ ( 12 ) NEW_LINE root1 . right . right = Node_ ( 25 ) NEW_LINE