Merge time intervals
Given a list of time intervals, merge all overlapping intervals and return the merged intervals.
Delete Old Records
Filter a list of records by removing those with a date older than a given cutoff date.
Top N per group
Implement top_n_per_group that returns the top N scores for each group from a list of (group, score) pairs.
Consecutive available seats
Given a list of seat statuses, return the length of the longest consecutive run of available (0) seats.
Argsort Indices
Implement a function that returns the indices that would sort a list of integers, with ties broken by original order.
Level Order Traversal
Implement a function that performs a level order traversal of a binary tree and returns node values as a list of lists.
Lowest Common Ancestor in a Binary Search Tree
Implement a function to find the lowest common ancestor of two node values in a binary search tree.
N-Queens Solutions
Implement a function to count the number of distinct ways to place n queens on an n×n board.
Matchsticks to Square
Given a list of matchstick lengths, decide if they can form a square by using each matchstick exactly once.
Merge K Sorted Lists
Write a function that merges multiple sorted lists into a single sorted list.
Memory view slice
Implement chunk_list that splits a list into consecutive sublists of a given chunk size.
Delete Middle Node
Implement a function that deletes a given non-tail node from a singly linked list in O(1) time.
Design Browser History
Implement a BrowserHistory class that supports visit, back, and forward navigation with step counts.
Design Skip List Lite
Implement a simplified skip list supporting insert, search, and delete with O(log n) average complexity.
Delete duplicates sorted II
Given a sorted list, remove duplicates in place so each element appears at most twice, returning the new length.
Largest Area Histogram Matrix
Given a binary matrix, compute the largest rectangle area consisting entirely of 1s.
Employees earning more than manager
Given employee records with manager IDs, find those who earn more than their direct manager.
Arithmetic Slices Count
Given a list of integers, count how many contiguous subarrays of length at least 3 form an arithmetic sequence.
Accounts Merge
Given a list of accounts, merge those that share any email and return sorted accounts.
Knight Tour Count
Implement a backtracking search to count all ways a knight can visit every cell on a 5x5 board exactly once starting from (0,0).
Strobogrammatic number II
Given a positive integer n, return all strobogrammatic numbers of length n in ascending order.
Showing 49–69 of 69 challenges · Data Structures & Algorithms
Data Structures & Algorithms — Python coding challenges
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This page lists data structures & algorithms 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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Challenges test what you can build under constraints. For guided teaching, use our Python tutorials. For quick checks, try quizzes or copy snippets from code samples.