rjeli

// Set<Document> added
// Featurizer f
// sc::parallelize : List<T> -> JavaRDD<T>

Stream<Tuple2<Integer,Vector>> featurizedStream = added.stream()
	.map(d -> new Tuple2(d.getId(), f.vector(d)));
		
JavaRDD<Tuple2<Integer,Vector>> featurized = 
	sc.parallelize(featurizedStream.collect(Collectors.toList()));

rjeli

profit :: [Int] -> Int
profit xs = f (head xs) 0 (tail xs)
  where 
    f minVal maxDiff [] = maxDiff
    f minVal maxDiff (x:xs) = f (min minVal x) (max maxDiff (x - minVal)) xs
    
-- O(n) time, O(1) memory