Python Coding Challenges

Remove Duplicates from String

Given a string, return a new string with each character that repeats consecutively reduced to a single occurrence.

strings loop filter

Longest Word Finder

Write a function that extracts alphabetic words from a string and returns the longest one, with ties broken by earliest position.

strings parsing max

Abbreviate Name

Create a function that takes a full name and returns an abbreviated version with initials and the last name.

strings formatting split

strings masking validation

Mask email address

Given an email address, return a masked version that hides everything but the first and last character of the local part and the domain.

Find substring index

Implement a function that returns the starting index of the first occurrence of a substring using only basic string indexing and slicing.

string search index

Sort characters in string

Write a function that sorts the characters in a string and returns the sorted string.

sorting string character

strings counting dictionary

Most Common Character

Return the character that appears most frequently in a string, breaking ties by earliest occurrence.

Index of First Occurrence

Implement a function that finds the starting index of a substring within a string, returning -1 when absent.

strings search index

string-parsing simulation lists

Safe Command Executor

Implement emulate_run that simulates running a command list and returns output and exit code.

string-parsing split strip

Parse Log Line

Write a function that parses a log line and returns a dictionary with timestamp, level, and message.

strings parsing camelcase

Split on camelCase

Given a camelCase string, split it into words at uppercase letters and return them as lowercase words.

strings validation returns

Validate username format

Implement a function that validates a username according to length, allowed characters, and no consecutive underscores.

Parse markdown headers

Write a function that parses markdown headers and returns their levels and texts.

markdown parsing strings

Parse bullet list

Parse a markdown-style bullet list and return the list of item texts, stripping bullet markers and trimming surrounding whitespace.

parsing strings markdown

string parsing strip split

Parse numbered list

Take a string containing a numbered list and return a clean list of the item texts.

string parsing word-count

Find repeated words

Return a lowercase list of unique words that appear more than once across a given text, ignoring case.

Crawler Log Folder

Given a list of folder navigation operations, compute the minimum steps required to return to the main folder.

strings stack simulation

Two Sum

Return indices (i, j) with i < j such that nums[i] + nums[j] == target.

dict complement

+18 pts 16m

Remove duplicates (sorted)

Return a sorted list with duplicates removed.

arrays two-pointer

Running Product of Integers

Given a list of integers, return a new list where each element at index i is the product of all elements from index 0 to i.

prefix product lists

Second Largest Unique Value

Return the second largest distinct integer from a list, or None if it doesn't exist.

sorting unique arrays

Keep only even indexes

Given a list, return a new list containing only the elements at even indices (0, 2, 4, ...).

list slicing indexing

+5 pts 5m

Running Maximum

Implement a function that returns a list where each element is the largest value seen so far.

lists cumulative maximum

Difference of Consecutive Elements

Given a list of numbers, return a new list where each element is the difference between consecutive elements.

list iteration math