Word frequency
Return a dict mapping each word to its count in the sentence.
List intersection
Return the sorted list of elements common to both lists.
First non-repeating character
Find the index of the first character that appears only once.
Most frequent element
Return the element that appears most often in a list.
Merge dicts summing values
Write a function that merges two dictionaries by summing values for duplicated keys.
Are two lists the same multiset
Write a function that checks if two lists contain the same elements with the same multiplicities, ignoring order.
Word to Index Map
Create a function that returns a dictionary mapping each unique word to the index of its first occurrence.
Group names by first letter
Given a list of names, return a dictionary mapping each first letter to all names starting with that letter in original order.
Missing keys default zero
Write a function to sum numeric values from dictionaries, treating missing keys as zero.
Keys Sorted by Value Descending
Given a dictionary mapping strings to integers, return a list of keys sorted by value descending, and when values tie, alphabetically ascending.
Nested get with dotted path
Implement a function that safely retrieves a value from a deeply nested dictionary using a dot-separated path, returning a default if any key is missing.
Anagram Dictionary Groups Lite
Group a list of words into anagrams using a dictionary keyed by sorted characters.
Common Keys of Two Dictionaries
Implement a function that finds keys shared by two dictionaries and returns them sorted.
Union of Many Sets
Implement a function that takes any number of sets and returns a sorted list of their union.
Mode of a list via counting
Implement a function that returns the mode of a list, resolving ties by the element that appears first.
Top k keys by count
Given a dictionary mapping keys to counts, return the top k keys with the highest counts, breaking ties alphabetically.
Values that appear once
Return a list of numbers that appear exactly once in the input list, in original order.
Replace keys with a mapping
Write a function that renames keys in a dictionary according to a mapping, with duplicate handling.
Two Sum with Dict
Implement the classic Two Sum problem: return indices of two numbers that add up to a target using a dict.
Anagram Groups by Size
Group a list of words into anagram groups and return them sorted by group size and lexicographically.
Top K Frequent Words
Given a list of words, return the k most frequent words sorted by frequency (descending) and then alphabetically.
Sort by frequency
Sort a list by element frequency descending, with ties broken by order of first occurrence.
Pair with difference K
Count unordered index pairs with absolute difference exactly K, handling duplicates correctly.
Set intersection size
Count how many distinct values appear in both of two given lists.
Symmetric Difference
Write a function that computes the symmetric difference of two lists, returning a sorted list of unique elements.
Disjoint Set Check
Check if two lists are disjoint by verifying they have no common elements.
Subset of another set
Write a function that checks if every element of one set is contained in another.
Frequency sort descending
Write a function that sorts a list by frequency descending while preserving original order for ties.
Count Pairs with Sum
Implement a function that counts the number of distinct pairs in a list summing to a target.
Ransom Note Builder
Given two strings, determine if the ransom note can be formed from the words in the magazine.
Showing 30 challenges · easy · Dicts & Sets
Dicts & Sets — Python coding challenges
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This page lists dicts & sets challenges — real Python problems you solve in the browser IDE with instant test feedback. Each challenge includes a clear brief, starter code, and automated checks.
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