All core DSA topics
System design basics (for senior roles)
Behavioral interview preparation
Every company has its own interview culture and focus areas. This chapter provides a targeted preparation strategy for each major tech company, based on documented patterns from thousands of interview reports.
Primary: Hard algorithms, system design, DP, graphsFrequency: DP, Trees, Graphs, Binary Search, Recursion, MathStyle: Pure algorithmic problem-solving with follow-up challenges
Problems often have multiple follow-ups that increase difficulty
Strong emphasis on code quality and handling edge cases
Interviewers expect you to analyze complexity proactively
System design rounds focus on scalability and trade-offs
Topic Frequency Example
Dynamic Programming Very High Interval DP, knapsack variants Graph Algorithms High BFS/DFS, shortest path, topological sort Trees High LCA, serialization, BST operations Binary Search Medium-High Search space reduction Math/Probability Medium Combinatorics, expected value
Practice explaining your thought process out loud
Always discuss time and space complexity before coding
Write clean, production-quality code — Google reviewers notice
Prepare for “what if” follow-ups (what if the input is huge? what if we need online processing?)
Study system design at scale (GFS, MapReduce, Bigtable concepts)
Given a matrix of 0s and 1s, find the largest rectangle containing only 1s.
Follow-up 1: What if the matrix is streaming (rows arrive one at a time)?
Follow-up 2: What if we need to answer multiple queries on sub-matrices?
Primary: Practical problems, graphs, trees, arraysFrequency: BFS/DFS, DP, Arrays, Strings, TreesStyle: Collaborative, iterative refinement
Strong emphasis on communication and collaborative problem-solving
Interviewers want to see you iterate on solutions (brute force → optimize)
Problems are often practical (related to social graphs, news feed, etc.)
Cultural fit is important — be humble, open to feedback
Topic Frequency Example
Arrays/Strings Very High Two pointers, sliding window BFS/DFS Very High Graph traversal, island problems Trees High Binary tree operations, BST DP High 1D/2D DP, string matching Design Medium News feed, friend suggestions
Start with the brute force solution, then optimize
Communicate constantly — explain your reasoning at each stepBe open to hints from the interviewer — they want to help
Practice iterative refinement : “I notice this can be improved by…”
Prepare behavioral stories using the STAR method
Given a list of user sessions (login/logout times), find the top K users
with the longest total session time.
Follow-up: How would you handle this with billions of users?
Primary: Leadership principles + codingFrequency: Arrays, Strings, Trees, Graphs, DPStyle: LP-driven behavioral + standard coding
Leadership Principles (LPs) are as important as codingEvery behavioral question maps to specific LPs
Coding problems are medium difficulty but require clean execution
Bar raiser round focuses on cultural fit
Principle Interview Relevance
Customer Obsession Design decisions, prioritization Ownership Taking initiative, going beyond scope Invent and Simplify Creative solutions, reducing complexity Are Right, A Lot Decision-making, trade-off analysis Learn and Be Curious Learning new technologies, growth mindset Hire and Develop the Best Mentoring, team building (senior roles) Insist on the Highest Standards Code quality, testing Think Big System design, vision Bias for Action Speed of execution, calculated risk Frugality Resource optimization Earn Trust Communication, transparency Dive Deep Debugging, root cause analysis Have Backbone; Disagree and Commit Technical disagreements Deliver Results Completing projects, meeting deadlines
Topic Frequency Example
Arrays/Strings Very High Subarray sum, string manipulation Trees Very High BST, N-ary trees, serialization Graphs High Course schedule, network delay DP Medium-High Coin change, longest subsequence System Design High (senior) E-commerce, distributed systems
Prepare 2-3 STAR stories for each LP — you’ll need them
Use “I” not “we” in behavioral answers
Include metrics and numbers in your stories
For coding: focus on correctness over optimization first
Practice Amazon-style system design (scale, availability, cost)
Design a system to recommend products to users based on their browsing history.
Coding: Implement a function to find the top K most frequently purchased items
in a given time window.
Primary: Systems knowledge, clean codeFrequency: Arrays, Strings, Trees, Design, Low-levelStyle: Attention to detail, edge cases, systems thinking
Strong focus on code quality and edge case handling
Interviewers are very detail-oriented
System design focuses on user experience and performance
Apple values elegance and simplicity in solutions
Topic Frequency Example
Arrays/Strings Very High Manipulation, parsing Trees High BST, trie, file systems System Design High iOS frameworks, iCloud Bit Manipulation Medium Hardware-related problems Concurrency Medium Thread safety, async patterns
Test your code mentally — trace through edge casesPay attention to naming conventions and code style
Consider memory efficiency — Apple cares about resource usage
Prepare for low-level questions (memory management, pointers)
Think about user experience in system design
Implement a thread-safe LRU cache with O(1) get and put operations.
Follow-up: How would you handle cache invalidation across multiple devices?
Primary: Standard algorithms, clean codeFrequency: Arrays, Strings, Trees, DP, GraphsStyle: Collaborative problem-solving, mentorship-oriented
Interviewers are often helpful and collaborative
Problems are fair and well-defined
Strong emphasis on testing and edge cases
Cultural fit emphasizes growth mindset and teamwork
Topic Frequency Example
Arrays/Strings Very High Sorting, searching, manipulation Trees Very High Binary tree, BST, serialization DP High Knapsack, LCS, edit distance Graphs Medium-High BFS/DFS, shortest path Design Medium Azure services, Office features
Communicate your approach before codingWrite test cases before implementing
Be open to feedback — Microsoft interviewers give hints
Practice debugging — they may ask you to fix broken code
Prepare for “why” questions — why this approach? why this data structure?
Given a binary tree, find the maximum path sum (path can start and end at any node).
Follow-up: What if the tree is a binary search tree?
Primary: Competitive programming styleFrequency: DP, Graphs, Trees, Advanced algorithmsStyle: Speed, optimization, hard problems
Problems are often competitive programming level
Strong emphasis on speed — you need to code fast
Interviewers expect optimal solutions quickly
Multiple rounds may be back-to-back (intensity)
Topic Frequency Example
DP Very High Interval DP, digit DP, bitmask DP Graphs Very High Shortest path, network flow Trees High Heavy-light decomposition, centroid Math Medium-High Number theory, combinatorics Data Structures Medium-High Segment tree, BIT, trie
Practice competitive programming on LeetCode, Codeforces
Focus on speed — solve medium problems in 15 minutes
Know advanced data structures (segment tree, BIT, sparse table)
Practice multiple approaches for each problem
Be ready for hard problems — ByteDance doesn’t hold back
Given an array of n integers, find the number of subarrays whose sum is divisible by k.
Constraints: n ≤ 10^5, k ≤ 10^9
Expected solution: O(n) using prefix sums and modular arithmetic
Primary: System design, senior-level thinkingFrequency: Design, Architecture, CodingStyle: Scalability thinking, trade-offs, high-level
Interview focuses heavily on system design and architecture
Coding problems are medium difficulty but require elegant solutions
Strong emphasis on scalability and reliability
Netflix values freedom and responsibility culture
Topic Frequency Example
System Design Very High Video streaming, recommendation engine Coding Medium Arrays, strings, basic algorithms Architecture High Microservices, event-driven systems Reliability High Failure handling, redundancy Data Medium ETL, real-time processing
Study Netflix’s tech blog — they publish a lot
Focus on distributed systems concepts
Prepare for trade-off discussions — there are no perfect answers
Think about cost optimization — Netflix cares about efficiency
Practice high-level design before diving into details
Design a system to deliver personalized video recommendations to 200M+ users.
Consider: data pipeline, model serving, A/B testing, real-time updates.
Dimension Google Meta Apple
Difficulty Hard Medium-Hard Medium Focus Algorithms Communication Detail Follow-ups Yes, progressive Yes, iterative Yes, edge cases Cultural Innovation Move fast Excellence
Aspect Expectation
Coding Medium difficulty, practical problems System Design Basic to intermediate Culture Scrappy, resourceful, adaptable Speed Faster process, fewer rounds
Aspect Expectation
Coding Hard, math-heavy Math Probability, statistics, combinatorics Puzzles Brain teasers, estimation Speed Very fast problem-solving
Week Focus Hours/Day
1-2 Arrays, Strings, Two Pointers 3-4 3-4 Trees, Graphs, BFS/DFS 3-4 5-6 DP, Greedy, Backtracking 3-4 7 System Design, Behavioral 4-5 8 Mock Interviews, Review 4-5
Morning (1 hour): Review 2-3 previously solved problems
Afternoon (2 hours): Solve 2-3 new problems (company-specific)
Evening (1 hour): Read system design / behavioral prep
1. UNDERSTAND: Restate the problem in your own words
2. EXAMPLES: Walk through 2-3 examples manually
3. APPROACH: Discuss brute force, then optimize
4. CODE: Write clean, well-structured code
5. TEST: Trace through your code with examples
6. ANALYZE: State time and space complexity
Company Focus Key Differentiator Difficulty
Google Algorithmic depth Hard problems + follow-ups ★★★★★ Meta Communication Iterative improvement ★★★★ Amazon Leadership principles LP + code combination ★★★★ Apple Systems thinking Clean implementation ★★★★ Microsoft Collaboration Problem-solving approach ★★★ ByteDance Speed Competitive programming ★★★★★ Netflix Scalability System design depth ★★★★
Research: Find 5 recent interview questions from your target company on LeetCode/Glassdoor. Solve each one.Mock: Conduct a mock interview with a friend, focusing on your weakest company-specific area.Behavioral: Write out STAR stories for 5 leadership principles (Amazon) or 5 company values.System Design: Design a URL shortener. Practice explaining it in 30 minutes.Speed: Solve 3 medium LeetCode problems in 45 minutes. Time yourself.
Q: How should I prepare differently for Google vs Amazon?
A: For Google, focus on hard algorithms and follow-up questions. For Amazon, balance coding with leadership principle stories — they’re equally important.
Q: What if I get a problem I’ve never seen before?
A: Start with brute force, identify patterns, break it into subproblems, and communicate your thought process. Interviewers value problem-solving approach over memorized solutions.
Q: How important is system design for a new grad?
A: Less important than coding, but still tested at some companies (especially Meta and Amazon). Focus on basic concepts: scalability, caching, databases, and load balancing.
All algorithm chapters in this book
System design: Chapter 140
Behavioral interviews: Chapter 141
Mock interview strategies: Chapter 143