(**) Decode a run-length encoded list.
Given a run-length code list generated as specified in problem 11. Construct its uncompressed version.
decodeModified :: [ListItem a] -> [a] decodeModified = concatMap decodeHelper where decodeHelper (Single x) = [x] decodeHelper (Multiple n x) = replicate n x
We only need to map single instances of an element to a list containing only one element and multiple ones to a list containing the specified number of elements and concatenate these lists.