Rippling Software Engineer Onsite Coding Questions

LeetCode #23: Merge k Sorted Lists. Difficulty: Hard. Topics: Linked List, Divide and Conquer, Heap (Priority Queue), Merge Sort. Asked at Rippling in the last 6 months.

LeetCode #737: Sentence Similarity II. Difficulty: Medium. Topics: Array, Hash Table, String, Depth-First Search, Breadth-First Search, Union-Find. Asked at Rippling in the last 6 months.

LeetCode #21: Merge Two Sorted Lists. Difficulty: Easy. Topics: Linked List, Recursion. Asked at Rippling in the last 6 months.

LeetCode #3: Longest Substring Without Repeating Characters. Difficulty: Medium. Topics: Hash Table, String, Sliding Window. Asked at Rippling in the last 6 months.

## Problem Derive the character ordering of an alien language from a sorted list of words using topological sort. ## Likely LeetCode equivalent LC 269 (Alien Dictionary) is the direct match. ## Tags graph, topological-sort, hash_table

## Problem Implement a canvas drawing system supporting shapes, fills, or flood-fill operations on a 2D grid. ## Likely LeetCode equivalent Related to LC 733 (Flood Fill). ## Tags matrix, DFS, simulation

## Problem Compute the block sum of a matrix where each cell holds the sum of neighboring cells within distance K. ## Likely LeetCode equivalent LC 1314 (Matrix Block Sum) is the direct match. ## Tags matrix, prefix-sum, arrays

## Problem Verify that the number of occurrences of each value in an array is unique. ## Likely LeetCode equivalent LC 1207 (Unique Number of Occurrences) is the direct match. ## Tags hash_table, arrays

## Problem You are asked to design a REST API layer for a task management service. Implement the following endpoints (you may use any framework or pseudocode): ``` POST /tasks Create a task {title, description, due_date, assignee_id} GET /tasks/:id Get task by ID PATCH /tasks/:id Update fields (partial update) DELETE /tasks/:id Soft-delete a task GET /tasks?status=&assignee= List with optional filters + pagination ``` **Expected Request/Response:** ``` POST /tasks Body: {"title": "Fix bug", "due_date": "2025-04-30", "assignee_id": "u42"} Response 201: {"id": "t123", "title": "Fix bug", "status": "open", ...} GET /tasks?status=open&page=2&limit=20 Response 200: {"items": [...], "total": 87, "page": 2, "limit": 20} ``` ## Follow-ups 1. How do you validate request bodies and return structured 422 errors? 2. Where and how would you add authentication/authorization (e.g., only assignee can update)? 3. How do you version the API when you need to introduce breaking changes? 4. Describe how you would rate-limit the list endpoint per client.

## Problem: Longest Consecutive Integer Sequence Given an **unsorted** integer array `nums`, return the length of the **longest sequence of consecutive integers**. A consecutive sequence is of the f

You are given a classification model output dataset as a Pandas DataFrame, containing ground-truth labels and model predictions (and possibly prediction scores). Using pandas: 1. Use `groupby` to agg

You are given a business fact table (exact schema not fixed in the post). You need to: 1. Aggregate the data by a specified dimension using an aggregate function (e.g., `COUNT`, `SUM`). 2. Based on t

## Problem: Add Search to a Store-only Logger (Read/Write Trade-offs) In the previous **store-only** logger, messages are appended to an internal storage. Add a `search(query)` feature to query store

## Problem: Implement a Configurable Logger (OOD) Implement a `Logger` that can process an input log message `message` according to a configured behavior, and then either print to stdout or store int

## Problem: Pay drivers up to a timestamp (payUpUntil) You are building a simple driver payroll module. The system continuously receives driving records. Each driver may have more than one driving re

## Problem: Validate Expense Reimbursements (Legality Check) You are given a list of employee expense reimbursement records. Implement validation logic to determine whether each reimbursement is **le

Given a list of intervals `intervals` where `intervals[i] = [start_i, end_i]` and `start_i <= end_i`, merge all overlapping intervals and return the merged list. Two intervals `[a,b]` and `[c,d]` ove

You need to maintain balances for delivery drivers (driverId is a string or integer) and answer very frequent queries for the total balance across all drivers. Design a data structure / API supportin

(Insufficient details: only mentions a poker-like card game; rules and I/O are missing, so it is omitted.)

## Problem: Food Delivery — Cost Calculation & Driver Payout You need to implement a set of computations for a food delivery platform, consisting of three parts. The system includes: - **Delivery (