Interview questions

Trapping Rain Water

Given an array of non-negative heights representing elevation bars of width 1, compute the total units of water that can be trapped between them after…

Companies: Amazon, Bloomberg, Goldman Sachs, Google +6

Array · Dynamic Programming · Monotonic Stack · Stack

Last reported Oct 2026

Unix Cd Command with Symbolic Link Resolution

Simulate the Unix cd command by implementing path resolution for relative paths ('.' and '..'), absolute paths, and symbolic links while detecting potential cycles. Use…

Companies: Meta, OpenAI

Last reported Oct 2026

Best Time to Buy and Sell Stock

Given an array of daily stock prices, compute the maximum profit achievable from exactly one buy-before-sell transaction (i.e., the largest prices[j] - prices[i] with j…

Companies: Adobe, Amazon, Apple, Atlassian +10

Array · Dynamic Programming

Last reported Sep 2026

Can Place Flowers

Given a binary array representing a flowerbed (0 = empty, 1 = planted) with no adjacent 1s, determine if you can add n new flowers…

Companies: LinkedIn, Meta

Array · Greedy

Last reported Sep 2026

Design a VM Manager

Design a VM manager class with methods to start a VM, stop a VM, and calculate a user's total expenditure across all their VMs. Billing…

Companies: Nebius

Last reported Sep 2026

Detect Anomalous Days in Hotel Reservations

Given a list of hotel reservations with check-in and check-out days, compute the number of active reservations per day and identify anomalous days where the…

Companies: Booking.com

Last reported Sep 2026

Find Deepest Level Substrings

Given a string of well-formed nested brackets and characters, return all substrings or characters enclosed within the innermost nested brackets. Note that there may be…

Companies: Bloomberg

Last reported Sep 2026

Find the Start and End Number of Continuous Ranges

Given an array of integers (possibly unsorted and with duplicates), identify all maximal sequences of consecutive numbers and return each range as its start and…

Companies: Nebius

Last reported Sep 2026

Implement an Inverted Index

Design and implement an inverted index data structure that maps each unique word to a list of documents or positions where it appears. The solution…

Companies: Confluent, Datadog

Last reported Sep 2026

Implement HTTP Route Matching for a Web Framework

Implement two functions, `registerHandler(pattern)` and `getHandler(path)`, that form the core routing logic of a web framework. `registerHandler` adds URL patterns (which may…

Companies: Google

Last reported Sep 2026

Implement RLE and Bit Packing Encoder

Implement an encoding algorithm that combines Run Length Encoding (RLE) and Bit Packing (BP). RLE encodes consecutive identical elements as RLE[element, frequency] and is…

Companies: Databricks

Last reported Sep 2026

Insert Delete GetRandom O(1)

Design a data structure supporting insert(val), remove(val), and getRandom() — which returns a uniformly random existing element — with each operation in average O(1) time…

Companies: Amazon, Apple, Bloomberg, Citadel +7

Array · Design · Hash Table · Math

Last reported Sep 2026

Instrumented KV Store

Implement a key-value store that supports standard get and put operations while also tracking the average latency or call count for each operation type.

Companies: Databricks

Last reported Sep 2026

Logger Rate Limiter

Implement a logger that decides whether to print a message at a given timestamp: return true if the message hasn't been printed in the last…

Companies: Amazon, Bloomberg, Google, Microsoft +3

Data Stream · Design · Hash Table

Last reported Sep 2026

Lowest Common Ancestor of a Binary Tree

Given a binary tree and two nodes p and q, find their lowest common ancestor (LCA) — the deepest node that has both p and…

Companies: Amazon, Apple, Atlassian, Canva +6

Binary Lifting · Binary Tree · Depth-First Search · Lowest Common Ancestor

Last reported Sep 2026

Match Payments to Invoices via Memo Line

Write a program that matches incoming payments to their corresponding open invoices based on the payment memo line. The system should handle cases where standalone…

Companies: Stripe

Last reported Sep 2026

Max Consecutive Ones III

Find the maximum length of a contiguous subarray that can be made all 1s by flipping at most k zeros — equivalently, find the longest…

Companies: Amazon, D. E. Shaw, LinkedIn, Meta

Array · Binary Search · Prefix Sum · Sliding Window

Last reported Sep 2026

Maximum Candies You Can Get from Boxes

Starting from given initial boxes, repeatedly open any box that is either already open or for which you have a key to collect its candies…

Companies: Airbnb

Array · Breadth-First Search · Graph Theory

Last reported Sep 2026

N-Queens

Place n queens on an n×n chessboard so no two queens share a row, column, or diagonal, and return all distinct board configurations. This is…

Companies: Microsoft, Netapp

Algorithm X · Array · Backtracking

Last reported Sep 2026

Number of Ships in a Rectangle

Given a black-box API hasShips(topRight, bottomLeft) that returns whether at least one ship (point at integer coordinates) lies inside an axis-aligned rectangle, compute the…

Companies: Bloomberg

Last reported Sep 2026

Remove All Adjacent Duplicates In String

Given a lowercase string, repeatedly remove any two equal adjacent characters until no more removals are possible and return the resulting (unique) string. Solve in…

Companies: Goldman Sachs, Meta, Whatnot

Last reported Sep 2026

Remove All Adjacent Duplicates in String II

Given a string s and integer k, repeatedly remove any run of k equal adjacent characters until no more removals are possible and return the…

Companies: Amazon, Apple, Meta, Oracle +2

Stack · String

Last reported Sep 2026