expected: [{:location=>"US", :id=>1, :name=>"Awesome Rubber Bottle", :price=>50.07, :card_name=>"Toni Senger II...ber=>"1234-2121-1221-1211", :transaction_date=>#<Date: 2012-07-29 ((2456138j,0s,0n),+0s,2299161j)>}]
got: [{:location=>"US", :id=>1, :name=>"Awesome Rubber Bottle", :price=>50.07, :card_name=>"Toni Senger II...ber=>"1234-2121-1221-1211", :transaction_date=>#<Date: 2016-07-24 ((2457594j,0s,0n),+0s,2299161j)>}]

That is the problem. We get 1 failure while submitting. There is no requirement for order by and I have tried both ASC and DESC, I get a different failure each time. Many of these US/EU sales based DB problems are poorly specified. There are hidden ordering requirements every where.

This is still confusing.

Order by US then EU just means show the US orders first. The requirement needs to state to show them ordered by ID, US first then EU.

No, even as a native speaker it is quite vague. The wikipedia article helps a little but is still not clear.

Even a stub of tests would be nice.

Mind the typos.

For clarity in dicussion. The following is the list in, the tree created, and the tree by levels result. Either buildTree needs to be fixed or the expectation that treeByLevels is the inverse of buildTree needs to change.

testIn = [2, 8, 9, 1, 3, 4, 5] -- becomes the following tree
testTree = Just (TreeNode (Just (TreeNode (Just (TreeNode Nothing Nothing 9))
                                          (Just (TreeNode Nothing Nothing 1)) 8))
                          (Just (TreeNode (Just (TreeNode Nothing Nothing 4))
                                          (Just (TreeNode Nothing Nothing 5)) 3)) 2)
-- which, by levels is
byLevelsResult = [2,8,3,9,1,4,5]

This makes lots of assumptions about the experience of the coder. The wikipedia link is not sufficient.

The supplied test case passes but the submit button never lights up.

Haskell language.

I had a hard time submitting this one due to a rendering/interaction bug. I am using Chrome on OSX. The pop-up note telling me how to submit was covering the "submit" button. The lower right corner would redraw and bounce around as I tried to click. I finally got lucky playing pixel whack-a-mole.

import Test.Hspec
import Digitize

test =
  (digitize 123 == [1,2,3]) &&
  (digitize 1 == [1]) &&
  (digitize 12 == [1,2])

main :: IO ()
main = hspec $ do
  describe "Test digitize" $ do
    it "123, 1, and 12" $ test `shouldBe` True