Interview questions

Simplify Path

Given an absolute Unix-style path, produce its canonical simplified form by collapsing multiple slashes and resolving "." (current dir) and ".." (parent dir) references. This…

Companies: Meta, NVIDIA, Roblox, Snowflake

Stack · String

Last reported Sep 2026

Task Scheduler II

Given an ordered list of task types and a cooldown "space", find the minimum total days (including required breaks) to finish all tasks while ensuring…

Companies: Amazon

Last reported Sep 2026

Implement a Thread Pool

Implement a thread pool using the concurrency primitives available in your programming language of choice. Your solution should support submitting tasks for execution and…

Companies: Temporal

Last reported Sep 2026

Shortest Uncommon Substring in an Array

For each string in an array, find the shortest substring that does not occur in any other string (choose the lexicographically smallest one among ties)…

Companies: Airbnb

Array · Hash Table · String · Trie

Last reported Sep 2026

Coin Path

Given an array of coin costs (with some positions possibly blocked) and a maximum jump length B, find a sequence of jumps from the first…

Companies: Oracle

Last reported Sep 2026

Days Until an Infection Spreads to Everyone on a Grid

Companies: OpenAI

Graphs · Grids & Matrices

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

Minimum Window Substring

Find the smallest substring of s that contains all characters of t (including duplicates), or return "" if none exists. This is typically solved with…

Companies: Amazon, LinkedIn, Lyft, Meta +2

Hash Table · Sliding Window · String

Last reported Sep 2026

Number of Subsequences That Satisfy the Given Sum Condition

Count the number of non-empty subsequences whose minimum plus maximum is ≤ target (answer mod 1e9+7). With n up to 1e5, the usual efficient approach…

Companies: LinkedIn

Last reported Sep 2026

Search in Rotated Sorted Array

Given an ascending array of distinct integers that has been rotated at an unknown pivot, return the index of a target value (or -1 if…

Companies: Amazon, Expedia, Google, LinkedIn +3

Array · Binary Search

Last reported Sep 2026

Validate KYC CSV Records

Implement a function that parses a CSV-formatted string containing business verification records and validates each record against a set of required fields and formatting rules.

Companies: Oracle, Stripe

Last reported Sep 2026

Spiral Matrix

Traverse the m×n matrix in clockwise spiral order (right, down, left, up) and return the elements in that sequence. The core challenge is managing changing…

Companies: Capital One, Liveramp, Meta, Microsoft +1

Array · Matrix · Simulation

Last reported Sep 2026

Binary Tree Level Order Traversal

Return the values of a binary tree grouped by depth, from left to right for each level (i.e., a level-order / breadth-first traversal). For an…

Companies: Meta, Visa, Zscaler

Last reported Sep 2026

Count Univalue Subtrees

Given a binary tree, count how many subtrees are "univalue" (every node in the subtree has the same value). The core challenge is to determine…

Companies: Grab

Last reported Sep 2026

Insert Delete GetRandom O(1) - Duplicates allowed

Design a data structure for a multiset that supports insert(val) (adding even duplicate occurrences), remove(val) (removing a single occurrence), and getRandom() (returning an…

Companies: CrowdStrike, LinkedIn, Okta

Array · Design · Hash Table · Math

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

Univalued Binary Tree

Check whether every node in a binary tree has the same value as the root; return true if all nodes match, false otherwise. This can…

Companies: Grab

Last reported Sep 2026

Minimum Time to Break Locks II

Given N locks and a set of operations (each with a time cost) that can simultaneously change the state of a subset of locks, find…

Companies: Microsoft

Last reported Sep 2026

2048 Game Backend

Implement the backend logic for the 2048 game, supporting swipe movements in all four directions (left, right, up, down). Tiles with the same value should…

Companies: Glean

Last reported Sep 2026

Babysitter Pay Calculator

Given a start time, end time, and tiered pay rates that vary based on time of day (e.g., different rates after midnight), calculate the total…

Companies: Upstart

Last reported Sep 2026

Bad Word Checker

Given an array of bad words and a user-provided string, determine if the string contains any bad words, accounting for common letter substitutions such as…

Companies: Discord

Last reported Sep 2026

Bitwise ORs of Subarrays

Count how many distinct integers appear as the bitwise OR of any non-empty contiguous subarray of arr. Key insight: bitwise OR only accumulates bits so…

Companies: Amazon, Microsoft

Last reported Sep 2026