Databricks Coding & Algorithms Interview Questions
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Design KV store with sliding-window average QPS
Problem Design an in-memory key–value store that supports mutation operations and can report the average QPS (queries per second) over a recent time w...
Implement streaming RLE and bit-packed codec
You are implementing a simple compression scheme for sequences of 32‑bit signed integers. The codec should support two encoding strategies: 1. Run‑Len...
Implement firewall matching with CIDR rules
Implement a simple IPv4 firewall rule matcher. Problem You are given an ordered list of firewall rules. Each rule has: - an action: ALLOW or DENY - a ...
Find path in implicit Fibonacci tree
You are given a special family of binary trees called Fibonacci trees. The k‑th order Fibonacci tree T(k) is defined recursively: - T(1) is a single n...
Implement run-length encoding and decoding
You are given a string consisting of lowercase English letters. You need to implement run-length encoding (RLE) and its corresponding decoding. 1. Enc...
Implement a rate-limited hit counter
You are designing a hit counter that records the number of hits received in the past 5 minutes. Implement a class HitCounter with the following method...
Check if CIDR is fully canceled by rules
You are given: - A target CIDR block T as a string, e.g. "10.0.0.0/16". - A list of rule CIDR blocks. Each rule has: - A type: either "allow" or "de...
Find first CIDR block covering IP
You are given: - A single IPv4 address as a string, e.g. "192.168.1.5". - A list of CIDR blocks (IPv4), each as a string in the form "a.b.c.d/x", wher...
Compute last-5-minute QPS in memory
Problem You are building a lightweight in-memory component that tracks the query load (QPS) of a service. Design a data structure with two operations:...
Design Tic-Tac-Toe and QPS data structures
You are given two independent coding problems that focus on data structure and API design. --- Problem 1: Generalized Tic-Tac-Toe Game with Simple AI ...
Find shortest path in a Fibonacci-ordered tree
You are given a recursively-defined binary tree T(order) whose shape depends only on order (not on node values). Nodes are labeled 0..N-1 using preord...
Find optimal commute mode in a city graph
You are designing a route planner that suggests the best way to commute between two points in a city using different transportation modes. The city is...
Implement RLE and bit-packing compression
You are asked to implement two related compression/decompression schemes: Run-Length Encoding (RLE) and bit-packing. --- Part 1 — Run-Length Encoding ...
Design IP/CIDR rule matcher
Design and implement a rule matcher that returns 'accept' or 'deny' for a given IPv4 address based on a set of rules. Each rule can be either an inclu...
Implement a sliding-window hit counter
Implement a hit counter that supports recordHit(timestamp) and getHits(pastSeconds). Use a fixed-size array to maintain a sliding time window (e.g., l...
Design BFS to detect forced win in Tic-Tac-Toe
You are given an n×n Tic-Tac-Toe–like board and a target k (1 ≤ k ≤ n). From the current board state and the player to move, design an algorithm to de...
Implement a snapshotable set with iterators
Implement a SnapshotSet data structure with the following API: add(x), remove(x), contains(x), snapshot() -> sid, and iterate(sid) -> iterator over th...
Design an efficient Tic-Tac-Toe engine
Design a Tic-Tac-Toe engine on an n x n board. Implement move(row, col, player) -> result where result indicates no winner, player1 wins, player2 wins...
Solve graph path, interval deletion, and robbery
Part A — Optimal path with transport modes: You are given a directed weighted graph of a city. Each edge has a travel time and a transport mode label ...
Design a rolling event tracker with ranges
Design a rolling event tracker that supports time-based queries. Implement a data structure with: ( 1) record(timestamp): record one event at integer ...