Interview questions

Custom Sort String

Reorder string s to follow the custom precedence defined by string order: every character that appears in order must appear in s in that relative…

Companies: Merge, Meta

Last reported Jul 2026

Maximum Depth of N-ary Tree

Given the root of an n-ary tree, return its maximum depth — the number of nodes along the longest root-to-leaf path. This is a simple…

Companies: Apple, Merge

Last reported Jul 2026

Meeting Rooms

Given a list of meeting time intervals [start, end], determine whether any two intervals overlap so a single person can attend all meetings; this is…

Companies: Amazon, Google, Meta, Procore +1

Last reported Jul 2026

Longest Substring with K Distinct Characters

Given a string s and a non-negative integer k, find the length of the longest substring that contains exactly k distinct characters. Return -1 if…

Companies: Adobe

Last reported Jul 2026

String Statistics: Sentence Count, Word Count, and Repeating Bigrams

Given a text string (e.g., a Lorem Ipsum passage), implement a series of functions to extract statistical information: the number of sentences, the number of…

Companies: Kaluza

Last reported Jul 2026

Serialize and Deserialize Binary Tree

Implement two complementary algorithms to convert a binary tree to a string and back, preserving exact node values and tree structure (including null children) so…

Companies: Amazon, LinkedIn, Meta, Microsoft +2

Last reported Jul 2026

Meeting Room Scheduling - Minimum Rooms Required

Given a list of meeting time intervals, determine the minimum number of conference rooms required so that no meetings overlap. This may involve handling 'Do…

Companies: Bloomberg, Google, Oracle

Last reported Jul 2026

Multi-Pattern String Replacement

Given a text string and a set of target words, find and replace all occurrences of those words in the text, treating whitespace as a…

Companies: Google

Last reported Jul 2026

Count Connected Friend Groups

Companies: OpenAI

Graphs

Last reported Jul 2026

Design a Social Network Class with Follow Relationships and Versioned Snapshots

Design a Social Network class that tracks follower relationships between users. Implement the following operations: follow(userA, userB), unfollow(userA, userB), snapshot()…

Companies: OpenAI

Last reported Jul 2026

Design an in-memory database to handle transactions

Design an in-memory database system that can efficiently handle transactions. Consider aspects such as data storage, transaction management, and concurrency control.

Companies: Anchorage Digital, Coinbase, Lyft, Uber

Last reported Jul 2026

Design an In-Memory File System with cd, ls, and File Lookup

Design a file system that supports basic operations including file lookup, directory navigation (cd command), and directory listing (ls command).

Companies: Anchorage Digital, Oracle

Last reported Jul 2026

Design Twitter as a coding class

Implement a Twitter class that supports posting tweets, following/unfollowing users, and retrieving the 10 most recent tweet IDs in a user's news feed. The core…

Companies: Coupang, Google, Headout

Last reported Jul 2026

Easy leetcode question, but doesn't allow language choice.

Companies: TikTok

Last reported Jul 2026

Find K Pairs with Smallest Sums

Given two non-decreasing arrays, return the k pairs (one element from each) with the smallest sums — the challenge is to efficiently produce the smallest…

Companies: LinkedIn

Array · Heap (Priority Queue)

Last reported Jul 2026

Implement HashMap Implement EventEmitter Promise related questions

Implement HashMap Implement EventEmitter Promise related questions

Companies: Microsoft

Last reported Jul 2026

Match Alphanumerical Pattern in Matrix I

Given an m×n grid of alphanumeric characters and a target pattern string, determine whether the pattern can be formed by a path of adjacent (up/down/left/right)…

Companies: Meta, Roblox

Array · Hash Table · Matrix · String

Last reported Jul 2026

Meeting Rooms III

Assign each meeting (with unique start times) to the lowest-numbered available room or delay it (keeping its duration and prioritizing earlier original start times) until…

Companies: Apple, Docusign, Google, Meta +2

Array · Hash Table · Heap (Priority Queue) · Simulation

Last reported Jul 2026

non-algorithmic coding question with two parts

Companies: Stripe

Last reported Jul 2026

Non-overlapping Intervals

Given a list of intervals (endpoints touching allowed), find the minimum number to remove so the remaining intervals are pairwise non-overlapping — equivalently, select the…

Companies: Amazon, Docusign, Grammarly

Array · Dynamic Programming · Greedy · Sorting

Last reported Jul 2026

Maximum Depth of Binary Tree

Given the root of a binary tree, return its maximum depth — the number of nodes along the longest root-to-leaf path. This classic easy problem…

Companies: Google, LinkedIn

Binary Tree · Breadth-First Search · Depth-First Search · Tree

Last reported Jun 2026

Minimum Moves to Equal Array Elements

Given an array where each move increments n−1 elements by 1 (equivalently decrementing a single element), compute the minimum moves to equalize all elements —…

Companies: Amazon

Last reported Jun 2026