Interview questions

Word Break II

Given a string s and a word dictionary, return all possible sentences formed by inserting spaces so every token is a dictionary word — i.e.…

Companies: Bloomberg, Meta, ServiceNow

Array · Backtracking · Dynamic Programming · Hash Table

Last reported Aug 2026

Majority Element

Given an array of n integers, return the element that appears more than ⌊n/2⌋ times (the majority element is guaranteed to exist). The goal is…

Companies: Amazon, Bloomberg, Coupang, Google +1

Array · Boyer–Moore Majority Vote Algorithm · Counting · Divide and Conquer

Last reported Aug 2026

Two Sum

Given an array of integers and a target, return the indices of two distinct elements whose values sum to the target (exactly one valid solution…

Companies: Amazon, Apple, Bloomberg, Brex +13

Array · Hash Table

Last reported Aug 2026

Maximum Number of Occurrences of a Substring

Find the substring (overlaps allowed) that occurs most often in s among those with length between minSize and maxSize and at most maxLetters distinct characters…

Companies: Chewy, LinkedIn, Microsoft

Hash Table · Sliding Window · String

Last reported Aug 2026

Accounts Merge

Given lists of accounts where each account has a name and emails, merge accounts that share any email by grouping connected emails (e.g., via union-find…

Companies: Airbnb, Bloomberg, Meta, Oracle +1

Array · Breadth-First Search · Depth-First Search · Hash Table

Last reported Aug 2026

Copy List with Random Pointer

Companies: Amazon, Meta, Microsoft, NVIDIA

Hash Table · Linked List

Last reported Aug 2026

Longest Consecutive Sequence

Find the length of the longest run of consecutive integers in an unsorted array, with an O(n) time requirement. The core idea is to detect…

Companies: Amazon, Bloomberg, Google, Microsoft +1

Array · Hash Table · Union-Find

Last reported Aug 2026

Time Based Key-Value Store

Design a time-based key-value store that records multiple values per key with timestamps and returns the value whose timestamp is the largest <= the queried…

Companies: Amazon, Anthropic, Apple, Citadel +8

Binary Search · Design · Hash Table · String

Last reported Aug 2026

Delete and Earn

Aggregate points for each distinct number (value * frequency), then choose a subset of values maximizing sum with the constraint that taking value x forbids…

Companies: Walmart, Walmart Labs

Array · Dynamic Programming · Hash Table

Last reported Jul 2026

Design Memory Allocator

Design an allocator for n memory units that supports allocating the leftmost contiguous block of a given size and freeing all units with a given…

Companies: Apple, OpenAI, Roblox

Array · Design · Hash Table · Simulation

Last reported Jul 2026

Analyze User Website Visit Pattern

Given timestamped website visits by users, find the 3-website sequence (in chronological order) that is visited by the largest number of unique users (count each…

Companies: Amazon, Spotify

Array · Hash Table · Sorting · String

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

Next Greater Element I

Given nums1 as a subset of nums2, for each element in nums1 return the first greater element that appears to its right in nums2 (or…

Companies: Flipkart, Microsoft

Array · Hash Table · Monotonic Stack · Stack

Last reported Jun 2026

Number of Distinct Islands

Given a binary grid, count how many distinct island shapes (connected components of 1s via 4-directional adjacency) appear, treating two islands as identical if they…

Companies: Anduril, Oracle, TikTok

Array · Breadth-First Search · Depth-First Search · Hash Function

Last reported Jun 2026

First Unique Number

Design a data structure that, given an initial list and a stream of added numbers, returns the first integer that appears exactly once at any…

Companies: Uber

Array · Data Stream · Design · Hash Table

Last reported Jun 2026

Happy Number

Determine whether iterating n -> sum of the squares of its digits eventually reaches 1 or falls into a repeating cycle; the core task is…

Companies: Snowflake

Floyd's Cycle Finding Algorithm · Hash Table · Math · Two Pointers

Last reported May 2026

Word Ladder

Find the length of the shortest transformation sequence from beginWord to endWord where each step changes exactly one letter and every intermediate word must be…

Companies: Amazon, Apple, Fan, Meta +5

Bidirectional Search · Breadth-First Search · Hash Table · String

Last reported May 2026

Valid Sudoku

Check a 9x9 Sudoku board is valid by verifying that no digit 1–9 (ignoring '.') appears more than once in any row, column, or 3x3…

Companies: Amazon, Cisco, Microsoft

Array · Hash Table · Matrix

Last reported May 2026

Throne Inheritance

Maintain an evolving rooted family tree (king as root) that supports adding a child and marking a person dead, and return the current inheritance order…

Companies: Apple, Snowflake

Depth-First Search · Design · Hash Table · Tree

Last reported May 2026

Longest Substring with At Most K Distinct Characters

Given a string and an integer K, find the length of the longest substring that contains at most K distinct characters. This is typically solved…

Companies: LinkedIn, TikTok

Hash Table · Sliding Window · String

Last reported Apr 2026

Smallest Common Region

Given lists where each entry names a parent region followed by its immediate subregions and two region names, find their smallest common region — the…

Companies: Airbnb

Array · Binary Lifting · Breadth-First Search · Depth-First Search

Last reported Apr 2026