Sets and Dictionaries Python lessons
Uniqueness, membership tests, key-value lookup, frequency counting, and grouping.
10 exercises8+ conceptsBeginner → interview context
Start this topicWHAT YOU WILL LEARN
Core concepts
Calculate set union and intersectionCount unique wordsBuild a word-frequency tableCalculate a student's averageUpdate inventoryGroup anagramsInvert a dictionaryFind the top k frequent values
REUSABLE THINKING
Problem-solving patterns
- set operators · sorting
- set · normalization
- Counter · dictionary
- nested data · average
- state update · business rule
LESSON OUTCOME
What this topic builds
Learn the idea once, trace it through two verified cases, then explain why your approach works.
ORDERED LESSONS
All 10 lessons in this topic
Work from top to bottom to build each concept gradually.
- #057Calculate set union and intersectionStarterPremium
Compare course IDs selected by two students.
- #058Count unique wordsStarterPremium
Count distinct words in a short, case-insensitive note.
- #059Build a word-frequency tableBeginnerPremium
Count every word in a short feedback line.
- #060Calculate a student's averageBeginnerPremium
Create a small record and report a learner's average.
- #061Update inventoryBeginnerPremium
Apply a sequence of deliveries and sales to current stock.
- #062Group anagramsBeginnerPremium
Group words that contain the same letters.
- #063Invert a dictionaryIntermediatePremium
Reverse a name-to-code mapping so codes become searchable keys.
- #064Find the top k frequent valuesIntermediatePremium
Find the two most frequent product codes.
- #065Merge numeric dictionariesIntermediatePremium
Add sales totals from two branches by product key.
- #066Build an adjacency listAdvancedPremium
Convert a small undirected network into neighbor lists.