Interview questions

Flatten Nested List Iterator

Given a nested list where elements may be integers or sublists, implement a NestedIterator with next() and hasNext() that returns all integers in depth‑first, left‑to‑right…

Companies: Adobe, LinkedIn

Depth-First Search · Design · Iterator · Queue

Last reported Aug 2026

Help Mouse Find the Cheese

Given a mouse in a grid, determine if the mouse can reach the cheese. The only way to manipulate the mouse is via two functions…

Companies: LinkedIn, Meta

Last reported Aug 2026

House Robber III

Companies: Microsoft, Snapchat

Last reported Aug 2026

Implement getElevator() and nextFloor() for a multi-elevator system

Given a list of elevators, each with a current floor and direction, implement two methods: getElevator(userFloor, destinationFloor) that selects the best elevator to serve a…

Companies: Pinterest

Last reported Aug 2026

Job Scheduling Algorithms Implementation

Implement job scheduling algorithms including both First Come First Serve (FCFS) and priority-based approaches. The solution should handle job submissions with start times, end…

Companies: Apple, Google, Netflix, Snowflake

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

Longest Increasing Subsequence II

Find the length of the longest strictly increasing subsequence of nums such that each adjacent difference is ≤ k. With n up to 1e5 and…

Companies: Google

Last reported Aug 2026

Longest Palindromic Substring

Given a string s, return the longest substring that reads the same forwards and backwards. The core challenge is efficiently finding palindromic spans around centers…

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

Dynamic Programming · Manacher · String · Two Pointers

Last reported Aug 2026

Maximize Transaction Fees Within Size Constraint

Given a list of transactions, each with an ID, fee, and size, implement a function that returns a subset of transactions that maximizes total fees…

Companies: Coinbase

Last reported Aug 2026

Minimum Cost to Balance a Circular Array of Warehouses

Given a circular array of 5 warehouses each containing a number of products, distribute the products evenly across all warehouses while minimizing the total cost…

Companies: Amazon

Last reported Aug 2026

Minimum Number of Increasing Subsequence to Be Removed

Given an integer array, find the minimum number of (not-necessarily-contiguous) strictly increasing subsequences you must remove to delete all elements. The core challenge is a…

Companies: Meta

Last reported Aug 2026

Random Pick with Blacklist

Given n and a blacklist of unique integers, design a data structure that returns a uniformly random integer from [0, n-1] excluding the blacklist while…

Companies: Google

Last reported Aug 2026

Return the Lexicographically Smallest Topological Order

Companies: OpenAI

Graphs · Heaps & Priority Queues

Last reported Aug 2026

Run-Length Encoding and Decoding

Implement a run-length encoder that compresses a string of ASCII characters, then implement a decoder that decompresses the encoded string in sub-linear time using binary…

Companies: Google

Last reported Aug 2026

Schedule meeting rooms to reduce fragmentation

Design a data structure to manage a list of meeting rooms, supporting methods to find and book the best available room for a given time…

Companies: Uber

Last reported Aug 2026

Shortest Cycle in a Graph

Find the graph's girth: given an undirected simple graph, return the length (number of edges) of the shortest cycle or -1 if none exists. With…

Companies: Microsoft

Last reported Aug 2026

Shortest Way to Form String

Given a source and target string, return the minimum number of subsequences of source that need to be concatenated to form target (or -1 if…

Companies: Pinterest

Binary Search · Greedy · String · Two Pointers

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

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

Valid Parentheses

Check whether a string of parentheses/brackets is valid by ensuring every closing bracket matches the most recent unmatched opening bracket and the types and nesting…

Companies: Amazon, Apple, Bloomberg, Google +9

Bracket Sequences · Stack · String

Last reported Aug 2026

Valid Tic-Tac-Toe State

Determine if a 3x3 Tic-Tac-Toe board is reachable under normal play by checking counts of X and O and detecting winning lines, ensuring any win(s)…

Companies: Microsoft

Last reported Aug 2026

Build an XOR generator and round-trip a tree document

Implement a pseudo-random generator that uses XOR operations. Use its output to transform a tree document and reverse that transformation. Verify that decoding restores the…

Companies: Baseten

Bit Manipulation · Serialization · Trees

Last reported Aug 2026