Sorting Algorithms Interview Guide: Quicksort, Mergesort, Counting Sort
Why Sorting Algorithms Matter in Interviews Sorting knowledge signals deep CS understanding. Interviewers ask about sorting to evaluate: time/space complexity […]
Algorithms
System Design
System Design Interview: Time Series Database (Prometheus / InfluxDB)
What Is a Time Series Database? A time series database (TSDB) stores sequences of timestamped values — metrics, sensor readings,
Algorithms
Hash Map Interview Patterns: Two Sum, Frequency Counting, Sliding Window
Why Hash Maps Are Fundamental Hash maps (dictionaries in Python, HashMaps in Java) provide O(1) average-case lookup, insertion, and deletion.
System Design
System Design Interview: Object Storage (Amazon S3)
What Is Object Storage? Object storage stores unstructured data (images, videos, backups, logs) as discrete objects with a flat namespace
System Design
System Design Interview: Notification Service (Push, SMS, Email at Scale)
Overview A notification service delivers time-sensitive messages to users via push notifications (mobile), SMS, email, and in-app alerts. WhatsApp sends
Algorithms
Topological Sort Interview Patterns: Kahn’s Algorithm, DFS Ordering, Cycle Detection
What Is Topological Sort? A topological sort of a directed acyclic graph (DAG) produces a linear ordering of vertices such
Algorithms
Matrix and Grid DP Interview Patterns: Unique Paths, Minimum Path Sum, Dungeon
Grid DP Overview Grid DP problems involve a 2D grid where you make decisions at each cell and need to
System Design
System Design Interview: Real-Time Analytics Dashboard (ClickHouse / Druid)
What Is Real-Time Analytics? Real-time analytics provides insights on data that is seconds to minutes old — not the hours
System Design
System Design Interview: Live Location Tracking (Uber / Lyft Driver GPS)
Overview Live location tracking ingests continuous GPS updates from millions of mobile devices and serves current location data to nearby
Algorithms
Segment Tree and Fenwick Tree (BIT) Interview Patterns
When Do You Need These? Segment trees and Fenwick trees (Binary Indexed Trees / BIT) solve range query problems efficiently.
Algorithms
Recursion Interview Patterns: Memoization, Tree Recursion, Classic Problems
The Recursion Mindset Recursion solves a problem by defining it in terms of a smaller version of the same problem.
System Design
System Design Interview: E-commerce and Inventory Management System
Core Components An e-commerce system handles product catalog, inventory tracking, shopping cart, order placement, payment processing, and fulfillment. Shopify processes
Algorithms
Divide and Conquer Interview Patterns: Merge Sort, Quick Select, Master Theorem
The Divide and Conquer Paradigm Divide and conquer solves problems by: (1) Divide — split the problem into smaller subproblems
Algorithms
Monotonic Stack Interview Patterns: Next Greater, Histograms, Stock Span
What Is a Monotonic Stack? A monotonic stack is a stack that maintains its elements in either monotonically increasing or
System Design
System Design Interview: Distributed Message Queue (Kafka / SQS)
Why Message Queues? A message queue decouples producers (services that generate events) from consumers (services that process them), enabling async