Missing Numbers

I received a message to solve the Missing Numbers challenge from HackerRank. The approach is to read the first list (A) to a HashMap so we would be able to get a count for each key. The process repeats with the second list (B). At that point we can iterate over list A (smaller) and update (subtract) or delete the matching keys from list B (larger). What is left in B is what is needed. Continue reading “Missing Numbers”