> This sounds like a job for Python. Indeed, an implementation takes fewer than 30 lines of code.

I don't know if the implementation is written in a "low-level" way to be more accessible to users of other programming languages, but it can certainly be done more simply leveraging the standard library:

  from collections import Counter
  import sys

  with open(sys.argv[1]) as f:
      words = Counter(word for line in f for word in line.split())

  for word, count in words.most_common():
      print(count, word)

At the very least, manually creating a (count, word) list from the dict items and then sorting and reversing it in-place is ignoring common idioms. `sorted` creates a copy already, and it can be passed a sort key and an option to sort in reverse order. A pure dict version could be:

  import sys

  with open(sys.argv[1]) as f:
    counts = {}
    for line in f:
      for word in line.split():
        counts[word] = counts.get(word, 0) + 1

  stats = sorted(counts.items(), key=lambda item: item[1], reverse=True)

  for word, count in stats:
      print(count, word)

(No, of course none of this is going to improve memory consumption meaningfully; maybe it's even worse, although intuitively I expect it to make very little difference either way. But I really feel like if you're going to pay the price for Python, you should get this kind of convenience out of it.)

Anyway, none of this is exactly revelatory. I was hoping we'd see some deeper investigation of what is actually being allocated. (Although I guess really the author's goal is to promote this Pystd project. It does look pretty neat.)