Interview questions

Number of Perfect Pairs

Count the number of index pairs (i<j) for which the absolute sum/difference of the pair satisfies both min(|a−b|,|a+b|) ≤ min(|a|,|b|) and max(|a−b|,|a+b|) ≥ max(|a|,|b|). The…

Companies: Meta

Last reported Jul 2026

Probability That Die A Beats Die B

Given two sorted arrays representing the face values of two fair dice A and B, calculate the probability that a single roll of die A…

Companies: Google

Last reported Jul 2026

Separate Squares II

Given axis-aligned squares (overlaps counted once), find the minimum y-coordinate of a horizontal line that splits the union area into equal halves. The core challenge…

Companies: Google

Last reported Jul 2026

String Template Substitution with Nested Variable Replacement and Cycle Detection

Implement a string substitution system that replaces placeholders (formatted as %var% or similar) in a text string with corresponding values from a given mapping. The…

Companies: Google

Last reported Jul 2026

Swap Adjacent in LR String

Given two strings of 'L', 'R', and 'X', determine if start can be transformed into result by repeatedly applying moves "XL" → "LX" (L moves…

Companies: Google

Last reported Jul 2026

Thread-Safe Account Transfer with Java and PostgreSQL

Implement a thread-safe fund transfer system between accounts using Java and PostgreSQL. Focus on transaction handling and data consistency for concurrent transfers, proper…

Companies: Revolut

Last reported Jul 2026

Intersection of Two Linked Lists

Companies: Amazon, LinkedIn, Microsoft

Last reported Jul 2026

Missing Ranges

Given a sorted array of distinct integers and inclusive lower/upper bounds, find all numbers or continuous ranges within [lower, upper] that are not present in…

Companies: Google, Meta

Last reported Jul 2026

N- ary tree

Each node of the tree represents a real machine in a cluster. Each machine in the cluster can only communicate with its parent and child…

Companies: OpenAI

Last reported Jul 2026

Word Search

Determine whether a target word can be formed by a path of horizontally or vertically adjacent cells in an m×n letter grid without reusing a…

Companies: Amazon, Glean, Google, Grammarly +3

Array · Backtracking · Depth-First Search · Matrix

Last reported Jul 2026

Chunk Upload Acknowledgment Tracker

Design a data structure to track chunk acknowledgments for a large file being uploaded in sequentially numbered, potentially out-of-order chunks. The structure must support…

Companies: Google

Last reported Jul 2026

Maximum Xor Product

Choose an integer x in [0, 2^n) to maximize (a XOR x) * (b XOR x) (answer mod 1e9+7); the core challenge is picking x’s…

Companies: Atlassian, Cisco, Zomato

Bit Manipulation · Greedy · Math

Last reported Jul 2026

Satisfiability of Equality Equations

Determine if a set of equations like "a==b" and "a!=b" over single-letter variables is satisfiable by grouping variables connected by equalities (e.g., with union-find) and…

Companies: Amazon

Last reported Jul 2026

Parsing A Boolean Expression

Parse and evaluate a fully parenthesized boolean expression string made of literals 't'/'f', unary '!' and comma-separated n-ary '&' and '|' operators with arbitrary nesting…

Companies: Microsoft

Last reported Jul 2026

Binary Search

Given a sorted (ascending) array of unique integers and a target value, return the index of the target or -1 if not present; the solution…

Companies: Amazon, Bloomberg, Google, Meta +1

Array · Binary Search

Last reported Jul 2026

Implement a UI Card Game That Deals Cards

Design and implement a user interface for a card game that includes functionality for dealing cards. Discuss the architecture, user interactions, and any animations or…

Companies: Airbnb, Apple

Last reported Jul 2026

Implement Rock Paper Scissors

Given a win condition and predefined game interfaces, implement a fully functional Rock Paper Scissors game. The solution should correctly handle game logic and player…

Companies: Apple

Last reported Jul 2026

My Calendar I

Design a data structure that supports booking half-open intervals [start, end) so that book(start, end) returns true and inserts the interval only if it causes…

Companies: Amazon, Google

Last reported Jul 2026

Range Sum Query - Immutable

Given an immutable integer array, implement a NumArray that returns the sum of elements in any [left, right] range. Because the array is static and…

Companies: Uber

Last reported Jul 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

Shortest Path in a Grid with Obstacles Elimination

Find the minimum number of steps from the top-left to bottom-right in a 4-directional binary grid if you may remove up to k obstacles; treat…

Companies: Amazon, Cisco, D. E. Shaw, Databricks +2

Array · Breadth-First Search · Matrix

Last reported Jul 2026

Debug and Tune an MNIST Image Classifier

Given a buggy NumPy-based neural network notebook for MNIST digit classification, identify and fix issues such as softmax overflow and incorrect gradient backpropagation using…

Companies: Datology

Last reported Jul 2026