Yahoo Interview Questions
Master your tech interview with our curated database of real questions from top companies.
Calculate Total Spend and Identify Key User Metrics
Transactions +----+---------+--------+------------+ | id | user_id | amount | date | +----+---------+--------+------------+ | 1 | 101 | 23....
Prove Equal Probability Impossible with Relabeled Dice Faces
Uniform Sums from Two Relabeled Fair Dice Setup You have two fair six-sided dice. You may relabel each die's faces with integers; duplicates are allow...
Solve Data Structure Challenges with Python Algorithms
Scenario You are given coding challenges in Python to manipulate simple data structures. Question Remove duplicates from a list of integers while pres...
Investigate Yahoo Mail's 10% DAU Decline Causes
Investigate a 10% DAU Drop in Yahoo Mail Scenario Yahoo Mail suddenly reports a 10% decline in daily active users (DAU). Task Walk through how you wou...
Diagnose a 10% DAU drop
On-Call Incident: Yahoo Mail DAU Down 10% on 2025-09-01 Assume all times are UTC, the product is global, and DAU is the canonical daily active user me...
Merge words by head-tail chaining
Given a list of lowercase words, merge them into a single string by repeatedly chaining words where the last character of the current string equals th...
Use OrderedDict to dedupe stably
Implement dedupe_preserve_order(seq) that removes duplicates from a list while preserving the order of first appearance, in O(n) time and O(k) space (...
Diagnose DAU drop with SQL by country
Write a single SQL query to diagnose a country-level DAU drop for an email product. Assume today is 2025-09-01. DAU is the count of distinct user_id w...
Calculate Expected Flips for Heads-Tails Sequence
Probability Check — Waiting Time for HT Setup - You repeatedly flip a fair coin (independent flips; P(H)=P(T)=1/2). - Stop as soon as the consecutive ...
Evaluate Widget Impact on User Engagement with A/B Testing
A/B Test Design: New In‑App Recommendation Widget Scenario A company is preparing to roll out a new in‑app recommendation widget and needs evidence th...
Explain Motivations and Cross-Functional Collaboration in Business Intelligence
Behavioral Interview Prompt: Motivation, Trajectory, and Communication Scenario You are interviewing for a Data Scientist role on a business intellige...