Code Challenges

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Solve real coding challenges in your browser. Earn XP, unlock badges, climb the leaderboard. Challenges in C#, TypeScript, Python, and JavaScript.

9 challenges Earn XP on every solve Leaderboard integration

TypeScript

Python

JavaScript

beginner3 challenges · 50 XP each

C#beginner

Reverse a String

Write a method that reverses a string without using built-in `Reverse()` methods. Handle null and empty strings gracefully.

Stringsstringstwo-pointer

+50 XPSolve

C#beginner

FizzBuzz with LINQ

Return a list of strings from 1 to n where multiples of 3 are 'Fizz', multiples of 5 are 'Buzz', and multiples of both are 'FizzBuzz'. Implement using LINQ.

LINQlinqclassic

+50 XPSolve

Pythonbeginner

Valid Parentheses

Given a string containing `(`, `)`, `{`, `}`, `[`, `]`, determine if the input string is valid. A string is valid if brackets are closed in the correct order.

Data Structuresstackclassic

+50 XPSolve

intermediate4 challenges · 150 XP each

C#intermediate

Two Sum

Given an array of integers and a target, return the indices of the two numbers that add up to the target. Each input has exactly one solution.

Algorithmshash-maparrays

+150 XPSolve

C#intermediate

Maximum Depth of Binary Tree

Given the root of a binary tree, return its maximum depth. The maximum depth is the number of nodes along the longest path from root to leaf.

Recursiontreesrecursion

+150 XPSolve

TypeScriptintermediate

Deep Flatten Array

Write a generic function that deeply flattens a nested array of any depth. Type it correctly with TypeScript generics.

Algorithmsarraysrecursion

+150 XPSolve

Pythonintermediate

Group Anagrams

Given a list of strings, group the anagrams together. An anagram is a word formed by rearranging the letters of another word.

Algorithmshash-mapsorting

+150 XPSolve

advanced1 challenges · 300 XP each

TypeScriptadvanced

Implement Debounce

Implement a `debounce` function. It returns a debounced version of a function that delays execution until after `delay` ms have elapsed since the last call.

Algorithmsclosurestimers

+300 XPSolve

expert1 challenges · 500 XP each

C#expert

LRU Cache

Design a data structure that implements a Least Recently Used (LRU) cache with Get and Put operations in O(1) time. Implement the LRUCache class.

Data Structuresdesignhash-map

+500 XPSolve

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