Sharpen Your Skills
Solve real coding challenges in your browser. Earn XP, unlock badges, climb the leaderboard. Challenges in C#, TypeScript, Python, and JavaScript.
Reverse a String
Write a method that reverses a string without using built-in `Reverse()` methods. Handle null and empty strings gracefully.
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.
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.
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.
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.
Deep Flatten Array
Write a generic function that deeply flattens a nested array of any depth. Type it correctly with TypeScript generics.
Group Anagrams
Given a list of strings, group the anagrams together. An anagram is a word formed by rearranging the letters of another word.
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