Tech Interview Questions

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Machine Learning Engineer + Data Scientist + Software Engineer Interview Questions

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9.0k Questions 480 Companies08.05.2026
Showing 20 results
Role
Roblox logo
Roblox
Medium
Data Scientist

Write SQL to flag suspect payments and chargebacks

Assume today is 2025-09-01. Using only CASE WHEN and JOINs (no window functions required), write a single SQL query that produces, for each user with ...

Data Manipulation (SQL/Python)
0
0
6 people solved
Oct 13, 2025
Twitch logo
Twitch
Medium
Data Scientist

Write robust SQL for streaming analytics

Write efficient PostgreSQL SQL for the following streaming analytics tasks. Use the invented schema and sample data below. Handle duplicates, out-of-o...

Data Manipulation (SQL/Python)
0
0
4 people solved
Oct 13, 2025
Capital One logo
Capital One
Medium
Data Scientist

Fix dash dates and aggregate watch time

You receive a CSV of ad viewing logs where the date column repeats only on the first row of each block and subsequent rows use a single dash '-' to in...

Data Manipulation (SQL/Python)
0
0
5 people solved
Oct 13, 2025
Capital One logo
Capital One
Medium
Data Scientist

Write one SQL for exam scores aggregation

You are given an exam database. Write a single SQL statement (CTEs allowed; one final statement only) that satisfies all three requirements below. You...

Data Manipulation (SQL/Python)
1
0
13 people solved
Oct 13, 2025
Microsoft logo
Microsoft
Hard
Data Scientist

Implement lower_bound on unknown-size sorted array

Lower Bound in Unknown-Length Nondecreasing Array via API Setup You are given a non-decreasing integer array A of unknown length n. You cannot access ...

Coding & Algorithms
3
0
52 people solved
Oct 13, 2025
Meta logo
Meta
Medium
Data Scientist

Compute multi-account activity and unread percentages in SQL

You are given two tables. Use them as the source of truth and do not assume any other data. Table: notifications +--------+------------+------------+-...

Data Manipulation (SQL/Python)
2
0
24 people solved
Oct 13, 2025
Intuit logo
Intuit
Medium
Data Scientist

Compute paid subscriber YoY counts by month

Write a single SQL query (PostgreSQL) that returns calendar-month counts of new paid subscribers starting from 2019-06-01 (inclusive) through the late...

Data Manipulation (SQL/Python)
1
0
17 people solved
Oct 13, 2025
DoorDash logo
DoorDash
Medium
Data Scientist

Implement minimum window substring with counts

Implement min_window_with_counts(s, t) Task Write a function: - min_window_with_counts(s: str, t: str) -> tuple[int, int] that returns the inclusive (...

Coding & Algorithms
8
0
103 people solved
Oct 13, 2025
Pinterest logo
Pinterest
Medium
Data Scientist

Find top video category by average time

You are given a pandas DataFrame 'pins' with columns [pin_id:int, category_id:int, time_spent_sec:float, pin_format:string] and a dict 'category_map' ...

Data Manipulation (SQL/Python)
0
0
4 people solved
Oct 13, 2025
Twitch logo
Twitch
Medium
Data Scientist

Solve advanced SQL for streaming analytics

You are given minute-level streaming telemetry. Each row in minute_streamed represents one minute during which a streamer was live; each row in minute...

Data Manipulation (SQL/Python)
0
0
5 people solved
Oct 13, 2025
Capital One logo
Capital One
Medium
Data Scientist

Merge ad CSVs and compute CTR

Using SQL, clean and merge four CSVs and answer all parts exactly. Schema and sample rows (assume types: date is DATE, others INT/VARCHAR): platforms(...

Data Manipulation (SQL/Python)
0
0
5 people solved
Oct 13, 2025
Capital One logo
Capital One
Medium
Data Scientist

Aggregate exam scores with NULL handling

Write a single SQL query (or CTE pipeline) to satisfy all requirements using the schema and sample data below. Replace any vendor-specific function wi...

Data Manipulation (SQL/Python)
0
0
7 people solved
Oct 13, 2025
Microsoft logo
Microsoft
Medium
Data Scientist

Implement rotated array binary search with duplicates

Given an integer array nums that is a non-decreasing array rotated an unknown number of times. Duplicates may exist. Implement a function that returns...

Coding & Algorithms
5
0
66 people solved
Oct 13, 2025
TCS logo
TCS
Medium
Data Scientist

Find duplicates in a list efficiently

Given a Python list that can contain integers (possibly negative) and may be very large, write code and explain approaches to find all values that app...

Coding & Algorithms
18
0
178 people solved
Oct 13, 2025
Meta logo
Meta
Medium
Data Scientist

Compute multi-account actives and unread coverage

You have two tables. Table: notifications +--------+------------+------------+-------------------+--------+ | userid | ds | time | notification_type |...

Data Manipulation (SQL/Python)
4
0
37 people solved
Oct 13, 2025
Google logo
Google
Medium
Data Scientist

Compute violation rate and flag precision in SQL

You are analyzing a Trust & Safety product in BigQuery. Assume 'today' is 2025-09-01 (UTC). Define precise metrics and write SQL to compute them, bein...

Data Manipulation (SQL/Python)
11
0
98 people solved
Oct 13, 2025
Meta logo
Meta
Medium
Data Scientist

Write SQL to flag coordinated fake accounts

Assume today is 2025-09-01. Schema and tiny samples: users(user_id, created_at, country) 1 | 2025-07-01 | US 2 | 2025-08-10 | IN 3 | 2025-08-15 | US 4...

Data Manipulation (SQL/Python)
0
0
7 people solved
Oct 13, 2025
Intuit logo
Intuit
Medium
Data Scientist

Exclude free subscribers via anti-join

Extend your previous monthly new-subscriber + YoY query to exclude companies that ever received a free subscription, using an anti-join against Free_S...

Data Manipulation (SQL/Python)
0
0
4 people solved
Oct 13, 2025
Intuit logo
Intuit
Medium
Data Scientist

Compute monthly new subscribers and YoY deltas

Write a single SQL query that returns monthly counts of new subscribers starting at 2019-06, plus year-over-year (same-month prior year) comparisons. ...

Data Manipulation (SQL/Python)
0
0
5 people solved
Oct 13, 2025
Meta logo
Meta
Medium
Data Scientist

Compute 7-day views and reactions by relationship

Use the schemas and sample data below to answer two tasks. Assume dates are strings in 'YYYY-MM-DD'. Treat "today" as 2025-09-01; "last/past 7 days" m...

Data Manipulation (SQL/Python)
0
0
5 people solved
Oct 13, 2025