Algorithmic Coding Challenges

Given an array of integers `nums` and an integer `target`, return indices of the two numbers such that they add up to `target`. You may assume that e...

Given the `head` of a singly linked list, reverse the list, and return the reversed list. ### Example 1 **Input:** head = [1,2,3,4,5] **Output:** [5,...

Given a function `fn` and a time in milliseconds `t`, return a **debounced** version of that function. A **debounced** function is a function whose e...

Develop a custom hook `useCounter` that supports increments, decrements, and optional reset bounds.

Given a nested array, flatten it into a single-level array. The function should support multiple levels of nesting. Example: Input: [1,[2,[3,[4]]]] ...

Create a function that creates a deep copy of an object without sharing references with the original object. The cloned object should work with neste...

Implement a utility function that converts a callback-based function into a Promise-based function. The returned function should resolve successful r...

Create an EventEmitter class that supports registering listeners, emitting events, and removing listeners. Methods required: - on() - emit() - off()

Implement a throttle utility that limits how frequently a function can execute. The function should execute immediately and ignore repeated calls unt...

Create a curry function that transforms a function with multiple arguments into a sequence of functions that each accept fewer arguments. Example: In...

Create a function that groups array elements based on a given key or callback function. Example: Input: [{age:20},{age:30},{age:20}] Output: {20:[......

Implement your own version of JavaScript Array.map without using the built-in map method. The function should accept a callback and return a new tran...

Create a simplified version of JSON.stringify. Convert JavaScript objects and arrays into JSON formatted strings.

Implement a memoize function that stores previous function results and returns cached values for repeated inputs. This improves performance by avoidi...

Implement your own version of Promise.all. It should take an array of promises and return a single promise that resolves when all input promises resol...

Implement Promise.race that resolves or rejects as soon as one promise settles.

Check if two values are deeply equal (objects, arrays, primitives).

Flatten a nested array up to a given depth.

Design and implement an LRU (Least Recently Used) cache.

Return a new array with duplicate values removed.

Split an array into chunks of given size.

Implement a compose function that combines multiple functions from right to left.

Implement a pipeline function that executes functions left to right.

Create a function that reverses the order of arguments passed to a function.

Create a React Todo component that allows users to add, delete, and mark tasks as completed. Requirements: - Add new todos - Remove todos - Toggle co...

Create a search component that filters a list of items based on user input.

Create a reusable pagination component that displays items page by page.

Build a reusable Modal component using React. Features: - Open and close modal - Handle outside click - Render children content

Implement a custom React hook that fetches API data and manages loading and error states.

Create a search input that delays API calls until the user stops typing.

Create an infinite scrolling list that loads more data when the user reaches the bottom.

Implement drag and drop functionality to reorder list items.

Create a React error boundary that catches component errors and displays fallback UI.

Create a small state management solution using React concepts. Features: - Store state - Update state - Subscribe components

Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. A string is valid if open brac...

You are given an array where each element is price of a stock on a day. Find maximum profit by choosing a single buy and sell day.

Given intervals, merge all overlapping intervals.

Implement binary search to find target in sorted array.

Find the contiguous subarray with the largest sum.

Detect if a linked list has a cycle.

Reverse a string using two pointers approach.

Rotate an array to the right by k steps.

Return the k most frequent elements in an array.

Find the length of the longest substring without repeating characters.

Find two numbers in a sorted array that add up to target.

Return all elements of a matrix in spiral order.

Count number of ways to reach nth stair.

Return array where each element is product of all other elements except itself.

Find minimum element in rotated sorted array using binary search.

Check if two strings are anagrams of each other.

Find two lines that together with x-axis forms container with max water.

Find index of first non-repeating character in a string.

Search target in a sorted 2D matrix.

Create a countdown timer that decreases every second using useEffect and useState. It should stop at zero and clean up properly.

Build a theme toggle button that switches between light and dark mode using React state.

Optimize a large list filtering operation using useMemo to avoid unnecessary recalculations.

Use useCallback to prevent unnecessary re-renders of child components when passing event handlers.

Create a form with validation for email, password strength, and required fields.

Implement authentication state management using React Context API.

Create a nested component structure where clicking a child button should not trigger parent click events. Demonstrate proper event handling using stop...

Build an input component that toggles between controlled and uncontrolled modes.

Build a custom hook that stores and returns the previous state value.

Create a multi-step form with next/back navigation and state persistence across steps.

Create a React Error Boundary that catches runtime errors and displays fallback UI.

Build a list that loads more data when user scrolls to bottom.

Filter a list of items based on user input search query.

Build a reusable hook to fetch API data with loading and error states.

Create a reusable modal with open/close functionality and overlay click handling.

Build a todo list optimized using React.memo and useCallback to prevent unnecessary re-renders.