Must-do problems: Dictionaries and Sets

90 min · Beginner

These are the dictionary and set problems every Python beginner should be able to solve, from a simple lookup to Two Sum, grouped anagrams and the longest consecutive run. Try each one on a small input by hand first, then check your program against every test.

What you will learn

Store and look up data with dictionaries, using get() and setdefault()
Build frequency maps and group items under a key
Use sets for fast membership checks, duplicates and set operations
Solve Two Sum and similar problems in one pass with a hash table

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