Interview questions

Group Anagrams

Group the input strings into lists of anagrams — i.e., strings that contain the same multiset of letters — and return the groups in any…

Companies: Amazon, Apple, Arize Ai, Bloomberg +14

Array · Hash Table · Sorting · String

Last reported Oct 2026

Top K Frequent Words

Count word frequencies and return the k most frequent words sorted by descending frequency, breaking ties by lexicographical order. The core challenge is combining frequency…

Companies: Apple, Microsoft, Oracle, Robinhood

Array · Bucket Sort · Counting · Hash Table

Last reported Oct 2026

Merge Intervals

Given a list of intervals, merge all overlapping (including touching endpoints) intervals and return the minimal set of non-overlapping intervals that cover them. Key pattern…

Companies: Amazon, Antithesis, Apple, Atlassian +16

Array · Quicksort · Sorting

Last reported Oct 2026

Card Game Program: Rank Three-Card Hands and Print the Winner

Companies: OpenAI

Low-Level Design (OOP) · Sorting

Last reported Oct 2026

Maximum Bitwise AND After Increment Operations

Given an integer array nums and two integers k and m, perform at most k increment operations on any elements, then return the maximum possible…

Companies: Amazon

Array · Bit Manipulation · Greedy · Sorting

Last reported Oct 2026

Maximum Coins From K Consecutive Bags

Given non-overlapping segments where every integer position in [li, ri] holds ci coins, find the maximum total coins covered by any contiguous window of k…

Companies: Amazon

Array · Binary Search · Greedy · Prefix Sum

Last reported Oct 2026

Put Boxes Into the Warehouse I

Given arrays of box heights and warehouse room heights, maximize how many boxes can be placed knowing a box can only reach a room if…

Companies: Pinterest

Array · Greedy · Sorting

Last reported Oct 2026

Top K Frequent Elements

Given an integer array and k, return the k most frequent elements — the core challenge is to count element frequencies and extract the top-k…

Companies: Amazon, Bloomberg, Google, Meta +9

Array · Bucket Sort · Counting · Divide and Conquer

Last reported Oct 2026

Maximum Number of Points From Grid Queries

For each query threshold, compute how many distinct cells you can reach from the top-left by moving 4-directionally through cells whose value is strictly less…

Companies: Uber

Array · Breadth-First Search · Heap (Priority Queue) · Matrix

Last reported Sep 2026

3Sum

Find all unique triplets in an integer array that sum to zero, ensuring no duplicate triplets in the output. The core challenge is efficiently enumerating…

Companies: Amazon, Apple, Bloomberg, Google +5

Array · Sorting · Two Pointers

Last reported Sep 2026

Kth Largest Element in an Array

Return the k-th largest element (by sorted order, not distinct) from an unsorted array. For inputs up to ~1e5 elements, solve it faster than full…

Companies: Bloomberg, LinkedIn, Meta, Salesforce +1

Array · Divide and Conquer · Heap (Priority Queue) · Quickselect

Last reported Sep 2026

Task Scheduler

Given tasks labeled A–Z and a cooldown n, compute the minimum number of CPU intervals (including idles) to finish all tasks so that identical tasks…

Companies: Amazon, Apple, Databricks, Docker +3

Array · Counting · Greedy · Hash Table

Last reported Sep 2026

Design Distributed Sorting Around an Explicit Helper Contract

Companies: Anthropic

Batch & Stream Processing · Sorting

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

K Closest Points to Origin

Given N points on the plane and an integer k, return the k points with the smallest Euclidean distance to the origin (order doesn't matter)…

Companies: Airbnb, Amazon, Asana, Meta

Array · Divide and Conquer · Geometry · Heap (Priority Queue)

Last reported Aug 2026

The Earliest Moment When Everyone Become Friends

Given timestamped friendship events among N people, determine the earliest time when the social graph becomes fully connected; process events in chronological order and use…

Companies: Amazon, Google, Uber

Array · Sorting · Union-Find

Last reported Aug 2026

Find Median from Data Stream

Maintain a data structure that supports adding integers from a stream and returning the current median efficiently for many interleaved addNum and findMedian calls. The…

Companies: Adobe, Amazon, D. E. Shaw, Intuit +4

Data Stream · Design · Heap (Priority Queue) · Sorting

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

Squares of a Sorted Array

Given an integer array sorted in non-decreasing order (which may contain negative numbers), return a new array of the squares of each number, also sorted…

Companies: Bloomberg, Instacart, Uber

Array · Sorting · Two Pointers

Last reported Aug 2026

Two Best Non-Overlapping Events

Given a set of weighted intervals, pick at most two non-overlapping events (events are inclusive, so the next must start at least end+1) to maximize…

Companies: Goldman Sachs, Grammarly

Array · Binary Search · Dynamic Programming · Heap (Priority Queue)

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

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