Jump Trading Online Assessment Questions

Card Set Detection: Determine if a Hand of Cards Forms Valid Sets Under Custom Rules

## Problem You are given a hand of cards. Each card has three attributes: `color` (red/green/blue), `shape` (oval/diamond/squiggle), and `count` (1/2/3). A valid "set" is any group of 3 cards where, for each attribute, the values across the 3 cards are either all the same or all different. Given a list of cards, find all valid sets in the hand. ```python from dataclasses import dataclass @dataclass class Card: color: str shape: str count: int def find_sets(hand: list[Card]) -> list[tuple[Card, Card, Card]]: ... ``` ``` Cards: A=(red, oval, 1) B=(green, oval, 2) C=(blue, oval, 3) D=(red, diamond, 2) (A,B,C): color=all diff, shape=all same, count=all diff -> VALID SET (A,B,D): color=all diff, shape=2 same 1 diff -> INVALID Output: [(A,B,C)] ``` ## Follow-ups 1. Your brute-force is O(n^3). For a 12-card layout, how many triples are there? Is O(n^3) acceptable in practice? 2. How would you detect if a hand has NO valid set (used in the game to trigger a redeal)? 3. Add a 4th attribute `fill` (solid/striped/empty). How does this change your validity check? 4. Given that each attribute has 3 values and there are 4 attributes, what is the maximum deck size, and what is the expected number of sets in a random 12-card deal?

Executable File Query Analyzer: SQL Queries on File Metadata with Aggregations

## Round 1 - SQL ## Problem You have a table `file_executions` that logs every time a binary is run on a system: ```sql CREATE TABLE file_executions ( exec_id BIGINT PRIMARY KEY, filename VARCHAR(255), user_id INT, run_at TIMESTAMP, duration_ms INT, exit_code INT ); ``` **Q1:** Find the top 5 most frequently executed files in the last 30 days. **Q2:** For each user, find the file they ran most often, and how many times. **Q3:** Find files that were run by more than 10 distinct users but had a non-zero exit code (failure) on more than 50% of executions. **Q4:** Compute the 7-day rolling average execution duration per file. ## Follow-ups 1. Q2 requires per-user ranking — write it with `ROW_NUMBER() OVER (PARTITION BY user_id ORDER BY run_count DESC)`. 2. Q3's 50% failure filter: should you compute failure rate before or after the distinct-user filter? Why does order matter? 3. For Q4, the rolling window must only include rows within 7 days of each row's `run_at`. Write the `RANGE BETWEEN` clause. 4. If this table has 500 million rows, which indexes would you add and why?

User Creation Endpoint: Implement and Validate a REST API Endpoint for User Registration

## Problem Implement a `POST /users` endpoint for user registration. The request body is JSON. Your implementation must: 1. Validate required fields: `email` (valid format), `password` (min 8 chars, at least one digit), `username` (alphanumeric, 3-20 chars). 2. Check that the email is not already registered (query a mock DB). 3. Hash the password before storing (do not store plaintext). 4. Return `201 Created` with `{"id": ..., "email": ..., "username": ...}` on success, or `400 Bad Request` with validation errors, or `409 Conflict` if email exists. ```python from flask import Flask, request, jsonify import hashlib, re app = Flask(__name__) USERS_DB = {} @app.route('/users', methods=['POST']) def create_user(): data = request.get_json() # Validate, check duplicate, hash, store, respond ... ``` ``` POST /users {"email":"[email protected]","password":"pass1234","username":"alice"} -> 201 {"id":"uuid","email":"[email protected]","username":"alice"} POST /users {"email":"[email protected]", ...} (duplicate) -> 409 {"error":"email already registered"} ``` ## Follow-ups 1. `hashlib.md5` is not suitable for passwords. What should you use instead and why (bcrypt/argon2)? 2. How do you return multiple validation errors in one response rather than stopping at the first? 3. Rate-limit this endpoint to 5 requests per IP per minute. Where does that logic live? 4. How would you write an integration test for this endpoint that covers the happy path and both error cases?