Interview questions

Multi-Source BFS

Implement a breadth-first search algorithm that starts simultaneously from multiple source nodes in a graph. Return the shortest distances from any source node to all…

Companies: DoorDash

Last reported Apr 2026

Next Greater Element II

Given a circular integer array, for each element find the first greater value encountered when traversing right (wrapping around the array circularly), or return -1…

Companies: Waymo

Last reported Apr 2026

Smallest Range Covering Elements from K Lists

Find the smallest interval [a, b] (minimize length, tie-break by smaller a) that contains at least one number from each of k sorted arrays. The…

Companies: Meta

Last reported Apr 2026

Valid Word Abbreviation

Check whether a given abbreviation (letters mixed with digits that denote how many characters to skip) correctly represents a target word. The core challenge is…

Companies: Apple, Meta

Last reported Apr 2026

Merge Sorted Array

Given two sorted arrays nums1 and nums2 and counts m and n (nums1 has length m+n with its last n slots free), merge the elements…

Companies: Amazon, Bloomberg, Google, Meta +2

Array · Sorting · Two Pointers

Last reported Apr 2026

Remove Interval

Given a sorted list of non-overlapping intervals and a target interval to remove, return the resulting intervals after subtracting the target from each input interval…

Companies: Meta

Last reported Apr 2026

Generate Data Labeling Schedules

Companies: OpenAI

Greedy · Job Scheduling & Workflows

Last reported Apr 2026

Minimum Area Rectangle

Given up to 500 unique 2D points, find the smallest area of an axis-aligned rectangle whose four corners are among the points. The core challenge…

Companies: Upstart

Last reported Apr 2026

String to Integer (atoi)

Parse a string into a 32-bit signed integer by skipping leading whitespace, reading an optional '+'/'-' sign and the following contiguous digits (stopping at the…

Companies: Meta, Microsoft, Netflix

Last reported Apr 2026

Find Minimum in Rotated Sorted Array II

Given a sorted array that has been rotated and may contain duplicates, find its minimum element — typically by using a modified binary search to…

Companies: Goldman Sachs

Last reported Apr 2026

Network Delay Time

Given a directed, nonnegative-weighted graph and a start node k, compute single-source shortest-path distances and return the maximum distance (the time for the signal to…

Companies: CrowdStrike, NVIDIA

Breadth-First Search · Depth-First Search · Dijkstra's Algorithm · Graph Theory

Last reported Apr 2026

Binary Search Tree Iterator

Implement an iterator over a BST that returns elements in in-order (ascending) via next() and hasNext(), starting before the smallest element so the first next()…

Companies: Meta, Uber

Last reported Apr 2026

IP Address Block List

Implement a system that manages a block list of IP addresses, supporting efficient lookups to determine if a given IP address is blocked. The solution…

Companies: Databricks

Last reported Apr 2026

Maximum OR

Given an array and up to k doublings (multiply an element by 2 each time), maximize the bitwise OR of all elements by choosing where…

Companies: Microsoft

Last reported Apr 2026

Build a Streaming Chat Input

Companies: OpenAI

React & UI Frameworks · State Management

Last reported Apr 2026

Generate Parentheses

Given a number n, generate all distinct well-formed parentheses strings formed from n pairs of opening and closing brackets. Return all valid combinations as a…

Companies: Amazon, Bloomberg, Microsoft, Salesforce

Backtracking · Bracket Sequences · Dynamic Programming · String

Last reported Apr 2026

Add Reply Functionality to Posts

Implement a full-stack reply feature for posts, including database schema changes, model and API layer modifications, and frontend updates with HTML components, CSS styling…

Companies: Dropbox

Last reported Apr 2026

Nearest Exit from Entrance in Maze

Given a grid maze with walls ('+') and empty cells ('.'), find the minimum number of up/down/left/right moves from the given entrance to the nearest…

Companies: Meta, TikTok

Last reported Apr 2026

Shopping Offers

Given unit prices, unlimited-use special bundle offers, and a target quantity for each of up to 6 items, compute the minimum cost to buy exactly…

Companies: Airbnb, Uber

Last reported Apr 2026

Convert IPv4 Ranges to CIDR Blocks

Companies: OpenAI

Bit Manipulation · Networking

Last reported Apr 2026

Implement a Family Tree

Given a Person class and a FamilyTree class, implement the getAncestors method on Person and the areRelated and commonAncestors methods on FamilyTree.

Companies: Microsoft, SoFi

Last reported Apr 2026

Making File Names Unique

Given an array of folder names, simulate creating them so that each duplicate gets the smallest positive integer suffix "(k)" to make it unique, and…

Companies: Juniper Square, Meta

Last reported Apr 2026