Snowflake Coding Interview Questions

You are given a list of courses (or tasks) with prerequisite/dependency relationships forming a directed graph. Core questions asked across variants include:…

You are given a 1D array where each element is 0 (empty), 1 (person), or 2 (cake). Part 1 (base): Find the…

You are given an n-ary tree (not necessarily binary) and a list of node IDs to delete. When a node is deleted,…

Implement a key-value store class supporting core CRUD operations: get(key), set/put(key, value), update(key, value), and delete/remove(key). The problem typically extends in multiple…

You are given a role hierarchy represented as a directed acyclic graph (DAG). Roles are numbered 0 to n-1. An array grants…

Given two complete binary trees with identical structure (same number of nodes, same topology), modify each node in the second tree so…

You are given an N-ary tree where each node is an independent distributed process running on a different host. Nodes can only…

Given a collection of elements (search words, hashtags, book titles, event keys, etc.) each associated with a count or frequency, find the…

Implement a Connect Four (four-in-a-row) game on an m×n board. The core problems seen across reports are: 1. Win detection (canPlayWin /…

A collection of coding problems centered on binary search, observed in Snowflake phone screens. The most concrete variant: given a log history…

Given a start wiki/web page and a target wiki/web page, find the minimum number of clicks (hops) needed to navigate from the…

Design and implement a rate limiter. In the most concrete variant: given an array where each index corresponds to a request ID…

Design and implement a class (OOP/OOD style) that calculates the amount of tax paid given a progressive (bracket-based) tax rate system. You…

Given two sorted arrays (or linked lists), merge them into a single sorted array/list. Follow-up: generalize to merging K sorted arrays/lists into…

Given an undirected graph represented as a list of nodes (locations) and a list of adjacency tuples (edges), determine whether the graph…

Given a 2D grid where cells are labeled B (Bathroom), D (Desk), or _ (empty space), find the shortest distance from each…

Given two arrays of strings (or a string and a pattern string), find all anagrams of the target(s) within the source and…

Design a system to process a stream of events. In the base version, implement two functions: (1) Receive(event_type, timestamp) — ingests an…

Implement a JavaScript EventEmitter class (or object) that supports the following methods: - subscribe(eventName, callback): Register a callback function to be called…

Design an in-memory file system that supports basic file system operations. This is based on LeetCode 588. You are required to implement…

Given a binary tree (or graph of linked nodes), find the shortest path between two given nodes. In one variant: given any…

Given an m×n matrix containing 0s and 1s, find the minimum distance (number of steps) from a start cell (sr, sc) to…

A sliding window problem appearing in Snowflake phone screens. The most detailed variant described involves finding all-vowel substrings within a given string,…

A LeetCode Hard-difficulty dynamic programming problem posed during a Snowflake phone screen / OA. The exact problem statement is not fully recoverable…

Given a positive integer n, determine whether it is a 'happy number'. A happy number is defined by the following process: starting…

Implement an interpreter for 'SnowCal', a simple programming language that keeps a single integer X in memory (initially 0) and supports the…

Implement a simple calculator / expression evaluator. In one observed variant, you are given a series of string commands such as 'ADD…

Implement a JSON parser (or JSON validator) that handles the following element types: - number: non-negative integer, leading zeros allowed (e.g., '004'…

Given a singly linked list where each node contains two pointers — 'next' pointing to the next node and 'random' pointing to…

A set of dynamic programming problems commonly appearing in Snowflake and similar companies' OAs (HackerRank format, Java or C++ only). Reported problems…

Given a database with employee and project information, write a SQL query to return the names of employees who have ever completed…

Given a list of LogEntry objects, each containing a UserId and a Time, find and return all users who have accessed the…

Solve the classic Two Sum problem, then extend the solution using a Trie data structure. The Trie implementation must not assume a…

Implement a Trie (prefix tree) data structure supporting insert, search, and startsWith operations. In a variant observed in this interview, the Trie…

Given a string containing parentheses, determine whether the parentheses are balanced (valid). The base version uses only '()'. The follow-up…

This question has two parts: Part 1 – Pattern Matching: Given a word (string of letters) and a pattern consisting of letters…

Implement inorder traversal of a binary tree (LeetCode 94). First, produce a correct solution with O(n) time and O(n) space (e.g., using…

Given a classic single-word transformation problem (e.g., transform one word into another by changing one letter at a time, where each intermediate…

Given an array of events where each event is represented as [startDay, endDay, value], and an integer k (maximum number of events…

Implement several common CSS visual elements from scratch: rectangular blocks, circles, and rounded-corner blocks (border-radius). Demonstrate knowledge of Flexbox alignment properties…

Given a simple pre-described system for storing user passwords, analyze the design: identify system bottlenecks and discuss how to address them. The…

Given N nodes, each associated with a privilege allowlist and a blocklist, and a list of directed edges [A, B] meaning 'B…

A variant of LeetCode 545 (Boundary of Binary Tree) where the condition is modified: instead of finding the boundary of a binary…

Implement an LRU (Least Recently Used) Cache that supports two operations: get(key) — return the value of the key if it exists…

Implement a JavaScript debounce utility function. The function should take a callback function and a delay (in milliseconds) as arguments, and return…

Given a string array representing hierarchical paths (e.g., ['California', 'California/San Francisco', 'California/San Francisco/7th Street']) and a second array of paths to delete…

Place N queens on an N×N chessboard such that no two queens attack each other (no two queens share the same row,…

You are given a RecordCollection class that contains a list of Color objects, where each color is encoded as an integer: 0…

Given a document string (containing arbitrary characters: letters, digits, punctuation, etc.) and a list of target words (plain words, no punctuation), perform…

Implement a class (OO design) with two methods: 1. addTask(taskId, priority, timestamp) — adds a task to a queue. The same taskId…

You are given an m×n grid representing a Connect-4-style game board (initially all zeros). Implement two methods: 1. drop(color, col): Drop a…

Given a mountain (peak/elevation) structure, calculate the height or maximum elevation. A commenter in the source thread asked what this question was…

Given a dataset of employee project contribution records, compute each employee's contribution per project, then sort/rank employees to identify who should be…

This is the third part of a multi-part problem set. Given a directed graph representing service dependencies (provided as an adjacency list,…

You are given a test pipeline consisting of three test jobs: - Test_Job1: executes a build phase, then runs test_a, test_b, test_c…

Implement a SQL database engine using virtual functions (C++ or similar OOP language). The task involves designing and implementing query operators (e.g.,…

Given a string, reverse only the consecutive alphanumeric substrings (substrings consisting solely of English letters and digits) in-place, while preserving all other…

Given two positive integers a and b, implement a function that outputs any valid path (sequence of operations) transforming a into b.…

Given an infinite supply of coins with denominations [1, 5, 10, 50, 100, 200], find the minimum total number of coins needed…

Design a data structure that supports two operations on a stream of integers: (1) addNum(int num) — add an integer to the…

Given an input string that may contain dots ('.') as delimiters between segments, determine whether the string is valid according to a…

Given a list of bus schedules, each represented as a (departure_time, arrival_time) pair, find the minimum number of buses needed to serve…

You are the Snowflake CEO managing a virtual warehouse. You are given n query types, each with different characteristics (e.g., execution time,…

Given a sorted/ordered ingredient list of n elements and a set of recipe specifications, where each recipe is defined as a consecutive…

Design a backend in-memory database to store temperature readings from a thermostat device. Each reading is a pair of [timestamp (format: YYYY-MM-DD…

Design a web server that manages a collection of documents and exposes two core APIs: 1. InsertDoc(filename): Inserts/registers a document (by filename)…

Implement a Throne Inheritance system using OOP. The system models a royal family where a King is the root, and inheritance follows…

Given a list of edges representing a tree, and a set of nodes marked as invalid/failed, compute the pre-order traversal of the…

An extended version of LeetCode 794 (Valid Tic-Tac-Toe State). Given a tic-tac-toe board state (represented as an array of strings), determine whether…

Given a forest represented as an array where each element stores its parent node's index (0-based). Root nodes are self-referential: parent[i] ==…

Given a 2D grid containing 'X' (marbles) and 'O' (empty cells). A marble can be removed if there exists at least one…

Implement serialization and deserialization of a Trie (prefix tree / dictionary trie) data structure. Given a Trie that stores a set of…

Given a binary tree, determine whether it is a 'perfect' binary tree — meaning every internal node has exactly 2 children and…

Given a binary tree, find the minimum number of add/remove operations to convert it into a perfect binary tree (i.e., every level…

Implement a Kanban board UI in React + TypeScript. The board displays tasks grouped by status columns (e.g., To Do, In Progress,…

Given a graph of services where edges represent dependencies (one service calling another), and given the first service that crashes (starts throwing…

Implement a key-value store that supports get, set, update, and delete operations, each accepting a timestamp as an extra parameter. Each key-value…

Count the number of ways to form a target string by selecting characters from columns of a word…

Given strings, perform a series of transformations according to a defined pattern (LeetCode 2851 'String Transformation'). The problem involves transforming one string…

You are given a data processing pipeline consisting of n services. The i-th service has an initial throughput of throughput[i], and each…

Given a collection of values, repeatedly find the maximum value and halve it (integer or floating-point division). Perform this operation some number…

An optimization problem requiring minimization of a 'weight' value under certain constraints. Full problem details were shared via screenshots in the original…

Design an OOD filter system with three methods: 1. processFilter(int value) — dynamically add or remove a value from a blacklist filter.…

Given a string pattern problem (Snowflake OA classic question), determine whether a target string can be formed or matched according to certain…

A schedule constraint satisfaction problem. Given a set of workers and scheduling constraints (such as shift assignments, availability windows, or coverage requirements),…

Given a string s, you need to transmit it over a network. The rules are: - If two adjacent characters in a…