Google Interview University
Translations: 中文版本
What is it?
This is my multimonth study plan for going from web developer (selftaught, no CS degree) to Google software engineer.
This long list has been extracted and expanded from Google's coaching notes, so these are the things you need to know. There are extra items I added at the bottom that may come up in the interview or be helpful in solving a problem. Many items are from Steve Yegge's "Get that job at Google" and are reflected sometimes wordforword in Google's coaching notes.
I've pared down what you need to know from what Yegge recommends. I've altered Yegge's requirements from information received from my contact at Google. This is meant for new software engineers or those switching from software/web development to software engineering (where computer science knowledge is required). If you have many years of experience and are claiming many years of software engineering experience, expect a harder interview. Read more here.
If you have many years of software/web development experience, note that large companies view software engineering as different from software/web development and they require computer science knowledge. Read more about that here
If you want to be a reliability engineer or systems engineer, study more from the optional list (networking, security).
Table of Contents
 What is it?
 Why use it?
 How to use it
 Get in a Googley Mood
 Did I Get the Job?
 Follow Along with Me
 Don't feel you aren't smart enough
 About Google
 About Video Resources
 Interview Process & General Interview Prep
 Pick One Language for the Interview
 Before you Get Started
 What you Won't See Covered
 Prerequisite Knowledge
 The Daily Plan
 Algorithmic complexity / BigO / Asymptotic analysis
 Data Structures
 More Knowledge

Trees
 Trees  Notes & Background
 Binary search trees: BSTs
 Heap / Priority Queue / Binary Heap
 balanced search trees (general concept, not details)
 traversals: preorder, inorder, postorder, BFS, DFS

Sorting
 selection
 insertion
 heapsort
 quicksort
 merge sort

Graphs
 directed
 undirected
 adjacency matrix
 adjacency list
 traversals: BFS, DFS
 Even More Knowledge
 System Design, Scalability, Data Handling (if you have 4+ years experience)
 Final Review
 Coding Question Practice
 Coding exercises/challenges
 Once you're closer to the interview
 Your Resume
 Be thinking of for when the interview comes
 Have questions for the interviewer
 Once You've Got The Job
 Everything below this point is optional 
 Additional Books

Additional Learning
 Compilers
 Floating Point Numbers
 Unicode
 Endianness
 Emacs and vi(m)
 Unix command line tools
 Information theory
 Parity & Hamming Code
 Entropy
 Cryptography
 Compression
 Networking (if you have networking experience or want to be a systems engineer, expect questions)
 Computer Security
 Garbage collection
 Parallel Programming
 Messaging, Serialization, and Queueing Systems
 Fast Fourier Transform
 Bloom Filter
 HyperLogLog
 LocalitySensitive Hashing
 van Emde Boas Trees
 Augmented Data Structures
 Tries
 Nary (Kary, Mary) trees

Balanced search trees
 AVL trees
 Splay trees
 Red/black trees
 23 search trees
 234 Trees (aka 24 trees)
 Nary (Kary, Mary) trees
 BTrees
 kD Trees
 Skip lists
 Network Flows
 Disjoint Sets & Union Find
 Math for Fast Processing
 Treap
 Linear Programming
 Geometry, Convex hull
 Discrete math
 Machine Learning
 Go
 Additional Detail on Some Subjects
 Video Series
 Computer Science Courses
Why use it?
I'm following this plan to prepare for my Google interview. I've been building the web, building services, and launching startups since 1997. I have an economics degree, not a CS degree. I've been very successful in my career, but I want to work at Google. I want to progress into larger systems and get a real understanding of computer systems, algorithmic efficiency, data structure performance, lowlevel languages, and how it all works. And if you don't know any of it, Google won't hire you.
When I started this project, I didn't know a stack from a heap, didn't know BigO anything, anything about trees, or how to traverse a graph. If I had to code a sorting algorithm, I can tell ya it wouldn't have been very good. Every data structure I've ever used was built into the language, and I didn't know how they worked under the hood at all. I've never had to manage memory unless a process I was running would give an "out of memory" error, and then I'd have to find a workaround. I've used a few multidimensional arrays in my life and thousands of associative arrays, but I've never created data structures from scratch.
But after going through this study plan I have high confidence I'll be hired. It's a long plan. It's going to take me months. If you are familiar with a lot of this already it will take you a lot less time.
How to use it
Everything below is an outline, and you should tackle the items in order from top to bottom.
I'm using Github's special markdown flavor, including tasks lists to check progress.

Create a new branch so you can check items like this, just put an x in the brackets: [x]
Fork a branch and follow the commands below
git checkout b progress
git remote add jwasham https://github.com/jwasham/googleinterviewuniversity
git fetch all
Mark all boxes with X after you completed your changes
git add .
git commit m "Marked x"
git rebase jwasham/master
git push force
More about Githubflavored markdown
Get in a Googley Mood
Print out a "future Googler" sign (or two) and keep your eyes on the prize.
Did I Get the Job?
I haven't applied yet.
Right now I'm doing programming problems all day long. That will continue for a few weeks, and then I'll apply through a referral I've been holding onto since February (yes, February).
Thanks for the referral, JP.
Follow Along with Me
I'm on the journey, too. Follow along:
 Blog: GoogleyAsHeck.com
 Twitter: @googleyasheck
 Twitter: @StartupNextDoor
 Google+: +Googleyasheck
 LinkedIn: johnawasham
Don't feel you aren't smart enough
 Google engineers are smart, but many have an insecurity that they aren't smart enough, even though they work at Google.
 The myth of the Genius Programmer
About Google
 For students  Google Careers: Technical Development Guide
 How Search Works:
 Series:
 Book: How Google Works
 Made by Google announcement  Oct 2016 (video)
About Video Resources
Some videos are available only by enrolling in a Coursera, EdX, or Lynda.com class. These are called MOOCs. Sometimes the classes are not in session so you have to wait a couple of months, so you have no access. Lynda.com courses are not free.
I'd appreciate your help to add free and alwaysavailable public sources, such as YouTube videos to accompany the online course videos.
I like using university lectures.
Interview Process & General Interview Prep

Videos:

Articles:
 Becoming a Googler in Three Steps

Get That Job at Google
 all the things he mentions that you need to know are listed below
 (very dated) How To Get A Job At Google, Interview Questions, Hiring Process
 Phone Screen Questions

Prep Courses:

Software Engineer Interview Unleashed (paid course):
 Learn how to make yourself ready for software engineer interviews from a former Google interviewer.

Software Engineer Interview Unleashed (paid course):

Additional (not suggested by Google but I added):
 ABC: Always Be Coding
 Four Steps To Google Without A Degree
 Whiteboarding
 How Google Thinks About Hiring, Management And Culture
 Effective Whiteboarding during Programming Interviews
 Cracking The Coding Interview Set 1:
 How to Get a Job at the Big 4:
 Failing at Google Interviews
Pick One Language for the Interview
I wrote this short article about it: Important: Pick One Language for the Google Interview
You can use a language you are comfortable in to do the coding part of the interview, but for Google, these are solid choices:
 C++
 Java
 Python
You could also use these, but read around first. There may be caveats:
 JavaScript
 Ruby
You need to be very comfortable in the language and be knowledgeable.
Read more about choices:
 http://www.bytebybyte.com/choosetherightlanguageforyourcodinginterview/
 http://blog.codingforinterviews.com/bestprogramminglanguagejobs/
 https://www.quora.com/WhatisthebestlanguagetoprograminforaninpersonGoogleinterview
You'll see some C, C++, and Python learning included below, because I'm learning. There are a few books involved, see the bottom.
Before you Get Started
This list grew over many months, and yes, it kind of got out of hand.
Here are some mistakes I made so you'll have a better experience.
1. You Won't Remember it All
I watched hours of videos and took copious notes, and months later there was much I didn't remember. I spent 3 days going through my notes and making flashcards so I could review.
Read please so you won't make my mistakes:
Retaining Computer Science Knowledge
2. Use Flashcards
To solve the problem, I made a little flashcards site where I could add flashcards of 2 types: general and code. Each card has different formatting.
I made a mobilefirst website so I could review on my phone and tablet, wherever I am.
Make your own for free:
 Flashcards site repo
 My flash cards database: Keep in mind I went overboard and have cards covering everything from assembly language and Python trivia to machine learning and statistics. It's way too much for what's required by Google.
Note on flashcards: The first time you recognize you know the answer, don't mark it as known. You have to see the same card and answer it several times correctly before you really know it. Repetition will put that knowledge deeper in your brain.
An alternative to using my flashcard site is Anki, which has been recommended to me numerous times. It uses a repetition system to help you remember. It's userfriendly, available on all platforms and has a cloud sync system. It costs $25 on iOS but is free on other platforms.
My flashcard database in Anki format: https://ankiweb.net/shared/info/25173560 (thanks @xiewenya)
3. Review, review, review
I keep a set of cheat sheets on ASCII, OSI stack, BigO notations, and more. I study them when I have some spare time.
Take a break from programming problems for a half hour and go through your flashcards.
4. Focus
There are a lot of distractions that can take up valuable time. Focus and concentration are hard.
What you won't see covered
This big list all started as a personal todo list made from Google interview coaching notes. These are prevalent technologies but were not mentioned in those notes:
 SQL
 Javascript
 HTML, CSS, and other frontend technologies
The Daily Plan
Some subjects take one day, and some will take multiple days. Some are just learning with nothing to implement.
Each day I take one subject from the list below, watch videos about that subject, and write an implementation in:
 C  using structs and functions that take a struct * and something else as args.
 C++  without using builtin types
 C++  using builtin types, like STL's std::list for a linked list
 Python  using builtin types (to keep practicing Python)
 and write tests to ensure I'm doing it right, sometimes just using simple assert() statements
 You may do Java or something else, this is just my thing.
Why code in all of these?
 Practice, practice, practice, until I'm sick of it, and can do it with no problem (some have many edge cases and bookkeeping details to remember)
 Work within the raw constraints (allocating/freeing memory without help of garbage collection (except Python))
 Make use of builtin types so I have experience using the builtin tools for realworld use (not going to write my own linked list implementation in production)
I may not have time to do all of these for every subject, but I'll try.
You can see my code here:
You don't need to memorize the guts of every algorithm.
Write code on a whiteboard or paper, not a computer. Test with some sample inputs. Then test it out on a computer.
Prerequisite Knowledge

Learn C
 C is everywhere. You'll see examples in books, lectures, videos, everywhere while you're studying.

C Programming Language, Vol 2
 This is a short book, but it will give you a great handle on the C language and if you practice it a little you'll quickly get proficient. Understanding C helps you understand how programs and memory work.
 answers to questions

How computers process a program:
Algorithmic complexity / BigO / Asymptotic analysis
 nothing to implement
 Harvard CS50  Asymptotic Notation (video)
 Big O Notations (general quick tutorial) (video)
 Big O Notation (and Omega and Theta)  best mathematical explanation (video)
 Skiena:
 A Gentle Introduction to Algorithm Complexity Analysis
 Orders of Growth (video)
 Asymptotics (video)
 UC Berkeley Big O (video)
 UC Berkeley Big Omega (video)
 Amortized Analysis (video)
 Illustrating "Big O" (video)
 TopCoder (includes recurrence relations and master theorem):

If some of the lectures are too mathy, you can jump down to the bottom and watch the discrete mathematics videos to get the background knowledge.
Data Structures

 Implement an automatically resizing vector.
 Description:

Implement a vector (mutable array with automatic resizing):
 Practice coding using arrays and pointers, and pointer math to jump to an index instead of using indexing.

new raw data array with allocated memory
 can allocate int array under the hood, just not use its features
 start with 16, or if starting number is greater, use power of 2  16, 32, 64, 128
 size()  number of items
 capacity()  number of items it can hold
 is_empty()
 at(index)  returns item at given index, blows up if index out of bounds
 push(item)
 insert(index, item)  inserts item at index, shifts that index's value and trailing elements to the right
 prepend(item)  can use insert above at index 0
 pop()  remove from end, return value
 delete(index)  delete item at index, shifting all trailing elements left
 remove(item)  looks for value and removes index holding it (even if in multiple places)
 find(item)  looks for value and returns first index with that value, 1 if not found

resize(new_capacity) // private function
 when you reach capacity, resize to double the size
 when popping an item, if size is 1/4 of capacity, resize to half

Time
 O(1) to add/remove at end (amortized for allocations for more space), index, or update
 O(n) to insert/remove elsewhere

Space
 contiguous in memory, so proximity helps performance
 space needed = (array capacity, which is >= n) * size of item, but even if 2n, still O(n)

 Description:
 C Code (video)  not the whole video, just portions about Node struct and memory allocation.
 Linked List vs Arrays:
 why you should avoid linked lists (video)
 Gotcha: you need pointer to pointer knowledge: (for when you pass a pointer to a function that may change the address where that pointer points) This page is just to get a grasp on ptr to ptr. I don't recommend this list traversal style. Readability and maintainability suffer due to cleverness.

implement (I did with tail pointer & without):
 size()  returns number of data elements in list
 empty()  bool returns true if empty
 value_at(index)  returns the value of the nth item (starting at 0 for first)
 push_front(value)  adds an item to the front of the list
 pop_front()  remove front item and return its value
 push_back(value)  adds an item at the end
 pop_back()  removes end item and returns its value
 front()  get value of front item
 back()  get value of end item
 insert(index, value)  insert value at index, so current item at that index is pointed to by new item at index
 erase(index)  removes node at given index
 value_n_from_end(n)  returns the value of the node at nth position from the end of the list
 reverse()  reverses the list
 remove_value(value)  removes the first item in the list with this value

Doublylinked List
 Description (video)
 No need to implement

 Stacks (video)
 Using Stacks LastIn FirstOut (video)
 Will not implement. Implementing with array is trivial.

 Using Queues FirstIn FirstOut(video)
 Queue (video)
 Circular buffer/FIFO
 Priority Queues (video)

Implement using linkedlist, with tail pointer:
 enqueue(value)  adds value at position at tail
 dequeue()  returns value and removes least recently added element (front)
 empty()

Implement using fixedsized array:
 enqueue(value)  adds item at end of available storage
 dequeue()  returns value and removes least recently added element
 empty()
 full()

Cost:
 a bad implementation using linked list where you enqueue at head and dequeue at tail would be O(n) because you'd need the next to last element, causing a full traversal each dequeue
 enqueue: O(1) (amortized, linked list and array [probing])
 dequeue: O(1) (linked list and array)
 empty: O(1) (linked list and array)


Videos:

Online Courses:

implement with array using linear probing
 hash(k, m)  m is size of hash table
 add(key, value)  if key already exists, update value
 exists(key)
 get(key)
 remove(key)

More Knowledge

 Binary Search (video)
 Binary Search (video)
 detail

Implement:
 binary search (on sorted array of integers)
 binary search using recursion

 Bits cheat sheet  you should know many of the powers of 2 from (2^1 to 2^16 and 2^32)
 Get a really good understanding of manipulating bits with: &, , ^, ~, >>, <<
 2s and 1s complement
 count set bits
 round to next power of 2:
 swap values:
 absolute value:
Trees

 Series: Core Trees (video)
 Series: Trees (video)
 basic tree construction
 traversal
 manipulation algorithms
 BFS (breadthfirst search)
 MIT (video)
 level order (BFS, using queue) time complexity: O(n) space complexity: best: O(1), worst: O(n/2)=O(n)
 DFS (depthfirst search)
 MIT (video)
 notes: time complexity: O(n) space complexity: best: O(log n)  avg. height of tree worst: O(n)
 inorder (DFS: left, self, right)
 postorder (DFS: left, right, self)
 preorder (DFS: self, left, right)

 Binary Search Tree Review (video)

Series (video)
 starts with symbol table and goes through BST applications
 Introduction (video)
 MIT (video)
 C/C++:
 Binary search tree  Implementation in C/C++ (video)
 BST implementation  memory allocation in stack and heap (video)
 Find min and max element in a binary search tree (video)
 Find height of a binary tree (video)
 Binary tree traversal  breadthfirst and depthfirst strategies (video)
 Binary tree: Level Order Traversal (video)
 Binary tree traversal: Preorder, Inorder, Postorder (video)
 Check if a binary tree is binary search tree or not (video)
 Delete a node from Binary Search Tree (video)
 Inorder Successor in a binary search tree (video)

Implement:
 insert // insert value into tree
 get_node_count // get count of values stored
 print_values // prints the values in the tree, from min to max
 delete_tree
 is_in_tree // returns true if given value exists in the tree
 get_height // returns the height in nodes (single node's height is 1)
 get_min // returns the minimum value stored in the tree
 get_max // returns the maximum value stored in the tree
 is_binary_search_tree
 delete_value
 get_successor // returns nexthighest value in tree after given value, 1 if none

 visualized as a tree, but is usually linear in storage (array, linked list)
 Heap
 Introduction (video)
 Naive Implementations (video)
 Binary Trees (video)
 Tree Height Remark (video)
 Basic Operations (video)
 Complete Binary Trees (video)
 Pseudocode (video)
 Heap Sort  jumps to start (video)
 Heap Sort (video)
 Building a heap (video)
 MIT: Heaps and Heap Sort (video)
 CS 61B Lecture 24: Priority Queues (video)
 Linear Time BuildHeap (maxheap)

Implement a maxheap:
 insert
 sift_up  needed for insert
 get_max  returns the max item, without removing it
 get_size()  return number of elements stored
 is_empty()  returns true if heap contains no elements
 extract_max  returns the max item, removing it
 sift_down  needed for extract_max
 remove(i)  removes item at index x
 heapify  create a heap from an array of elements, needed for heap_sort

heap_sort()  take an unsorted array and turn it into a sorted array inplace using a max heap
 note: using a min heap instead would save operations, but double the space needed (cannot do inplace).
Sorting

Notes:
 Implement sorts & know best case/worst case, average complexity of each:
 no bubble sort  it's terrible  O(n^2), except when n <= 16
 stability in sorting algorithms ("Is Quicksort stable?")

Which algorithms can be used on linked lists? Which on arrays? Which on both?
 I wouldn't recommend sorting a linked list, but merge sort is doable.
 Merge Sort For Linked List
 Implement sorts & know best case/worst case, average complexity of each:
For heapsort, see Heap data structure above. Heap sort is great, but not stable.

UC Berkeley:
 Analyzing Bubble Sort (video)
 Insertion Sort, Merge Sort (video)
 Insertion Sort (video)
 Merge Sort (video)
 Quicksort (video)

Merge sort code:

Quick sort code:

Implement:
 Mergesort: O(n log n) average and worst case
 Quicksort O(n log n) average case
 Selection sort and insertion sort are both O(n^2) average and worst case
 For heapsort, see Heap data structure above.

Not required, but I recommended them:
If you need more detail on this subject, see "Sorting" section in Additional Detail on Some Subjects
Graphs
Graphs can be used to represent many problems in computer science, so this section is long, like trees and sorting were.

Notes from Yegge:
 There are three basic ways to represent a graph in memory:
 objects and pointers
 matrix
 adjacency list
 Familiarize yourself with each representation and its pros & cons
 BFS and DFS  know their computational complexity, their tradeoffs, and how to implement them in real code
 When asked a question, look for a graphbased solution first, then move on if none.
 There are three basic ways to represent a graph in memory:

Skiena Lectures  great intro:
 CSE373 2012  Lecture 11  Graph Data Structures (video)
 CSE373 2012  Lecture 12  BreadthFirst Search (video)
 CSE373 2012  Lecture 13  Graph Algorithms (video)
 CSE373 2012  Lecture 14  Graph Algorithms (con't) (video)
 CSE373 2012  Lecture 15  Graph Algorithms (con't 2) (video)
 CSE373 2012  Lecture 16  Graph Algorithms (con't 3) (video)

Graphs (review and more):
 6.006 SingleSource Shortest Paths Problem (video)
 6.006 Dijkstra (video)
 6.006 BellmanFord (video)
 6.006 Speeding Up Dijkstra (video)
 Aduni: Graph Algorithms I  Topological Sorting, Minimum Spanning Trees, Prim's Algorithm  Lecture 6 (video)
 Aduni: Graph Algorithms II  DFS, BFS, Kruskal's Algorithm, Union Find Data Structure  Lecture 7 (video)
 Aduni: Graph Algorithms III: Shortest Path  Lecture 8 (video)
 Aduni: Graph Alg. IV: Intro to geometric algorithms  Lecture 9 (video)
 CS 61B 2014 (starting at 58:09) (video)
 CS 61B 2014: Weighted graphs (video)
 Greedy Algorithms: Minimum Spanning Tree (video)
 Strongly Connected Components Kosaraju's Algorithm Graph Algorithm (video)

Full Coursera Course:

Yegge: If you get a chance, try to study up on fancier algorithms:
 Dijkstra's algorithm  see above  6.006
 A*

I'll implement:
 DFS with adjacency list (recursive)
 DFS with adjacency list (iterative with stack)
 DFS with adjacency matrix (recursive)
 DFS with adjacency matrix (iterative with stack)
 BFS with adjacency list
 BFS with adjacency matrix
 singlesource shortest path (Dijkstra)
 minimum spanning tree
 DFSbased algorithms (see Aduni videos above):
 check for cycle (needed for topological sort, since we'll check for cycle before starting)
 topological sort
 count connected components in a graph
 list strongly connected components
 check for bipartite graph
You'll get more graph practice in Skiena's book (see Books section below) and the interview books
Even More Knowledge

 Stanford lectures on recursion & backtracking:
 when it is appropriate to use it
 how is tail recursion better than not?

 This subject can be pretty difficult, as each DP soluble problem must be defined as a recursion relation, and coming up with it can be tricky.
 I suggest looking at many examples of DP problems until you have a solid understanding of the pattern involved.

Videos:
 the Skiena videos can be hard to follow since he sometimes uses the whiteboard, which is too small to see
 Skiena: CSE373 2012  Lecture 19  Introduction to Dynamic Programming (video)
 Skiena: CSE373 2012  Lecture 20  Edit Distance (video)
 Skiena: CSE373 2012  Lecture 21  Dynamic Programming Examples (video)
 Skiena: CSE373 2012  Lecture 22  Applications of Dynamic Programming (video)
 Simonson: Dynamic Programming 0 (starts at 59:18) (video)
 Simonson: Dynamic Programming I  Lecture 11 (video)
 Simonson: Dynamic programming II  Lecture 12 (video)
 List of individual DP problems (each is short): Dynamic Programming (video)
 Yale Lecture notes:
 Coursera:

 Optional: UML 2.0 Series (video)

ObjectOriented Software Engineering: Software Dev Using UML and Java (21 videos):
 Can skip this if you have a great grasp of OO and OO design practices.
 OOSE: Software Dev Using UML and Java

SOLID OOP Principles:
 Bob Martin SOLID Principles of Object Oriented and Agile Design (video)
 SOLID Design Patterns in C# (video)
 SOLID Principles (video)
 S  Single Responsibility Principle  Single responsibility to each Object
 O  Open/Closed Principal  On production level Objects are ready for extension for not for modification
 L  Liskov Substitution Principal  Base Class and Derived class follow ‘IS A’ principal
 I  Interface segregation principle  clients should not be forced to implement interfaces they don't use
 D Dependency Inversion principle  Reduce the dependency In composition of objects.

 Quick UML review (video)

Learn these patterns:
 strategy
 singleton
 adapter
 prototype
 decorator
 visitor
 factory, abstract factory
 facade
 observer
 proxy
 delegate
 command
 state
 memento
 iterator
 composite
 flyweight
 Chapter 6 (Part 1)  Patterns (video)
 Chapter 6 (Part 2)  AbstractionOccurrence, General Hierarchy, PlayerRole, Singleton, Observer, Delegation (video)
 Chapter 6 (Part 3)  Adapter, Facade, Immutable, ReadOnly Interface, Proxy (video)
 Series of videos (27 videos)

Head First Design Patterns
 I know the canonical book is "Design Patterns: Elements of Reusable ObjectOriented Software", but Head First is great for beginners to OO.
 Handy reference: 101 Design Patterns & Tips for Developers

 Math Skills: How to find Factorial, Permutation and Combination (Choose) (video)
 Make School: Probability (video)
 Make School: More Probability and Markov Chains (video)

Khan Academy:
 Course layout:
 Just the videos  41 (each are simple and each are short):

 Know about the most famous classes of NPcomplete problems, such as traveling salesman and the knapsack problem, and be able to recognize them when an interviewer asks you them in disguise.
 Know what NPcomplete means.
 Computational Complexity (video)
 Simonson:
 Skiena:
 Complexity: P, NP, NPcompleteness, Reductions (video)
 Complexity: Approximation Algorithms (video)
 Complexity: FixedParameter Algorithms (video)
 Peter Norvik discusses nearoptimal solutions to traveling salesman problem:
 Pages 1048  1140 in CLRS if you have it.



Computer Science 162  Operating Systems (25 videos):
 for processes and threads see videos 111
 Operating Systems and System Programming (video)
 What Is The Difference Between A Process And A Thread?
 Covers:
 Processes, Threads, Concurrency issues
 difference between processes and threads
 processes
 threads
 locks
 mutexes
 semaphores
 monitors
 how they work
 deadlock
 livelock
 CPU activity, interrupts, context switching
 Modern concurrency constructs with multicore processors
 Process resource needs (memory: code, static storage, stack, heap, and also file descriptors, i/o)
 Thread resource needs (shares above (minus stack) with other threads in the same process but each has its own pc, stack counter, registers, and stack)
 Forking is really copy on write (readonly) until the new process writes to memory, then it does a full copy.
 Context switching
 How context switching is initiated by the operating system and underlying hardware
 Processes, Threads, Concurrency issues
 threads in C++ (series  10 videos)
 concurrency in Python (videos):

Computer Science 162  Operating Systems (25 videos):

 These are Google papers and wellknown papers.
 Reading all from end to end with full comprehension will likely take more time than you have. I recommend being selective on papers and their sections.
 1978: Communicating Sequential Processes

2003: The Google File System
 replaced by Colossus in 2012

2004: MapReduce: Simplified Data Processing on Large Clusters
 mostly replaced by Cloud Dataflow?
 2007: What Every Programmer Should Know About Memory (very long, and the author encourages skipping of some sections)

2012: Google's Colossus
 paper not available
 2012: AddressSanitizer: A Fast Address Sanity Checker:
 2013: Spanner: Google’s GloballyDistributed Database:
 2014: Machine Learning: The HighInterest Credit Card of Technical Debt
 2015: Continuous Pipelines at Google
 2015: HighAvailability at Massive Scale: Building Google’s Data Infrastructure for Ads
 2015: TensorFlow: LargeScale Machine Learning on Heterogeneous Distributed Systems
 2015: How Developers Search for Code: A Case Study
 2016: Borg, Omega, and Kubernetes

 To cover:
 how unit testing works
 what are mock objects
 what is integration testing
 what is dependency injection
 Agile Software Testing with James Bach (video)
 Open Lecture by James Bach on Software Testing (video)
 Steve Freeman  TestDriven Development (that’s not what we meant) (video)
 TDD is dead. Long live testing.
 Is TDD dead? (video)
 Video series (152 videos)  not all are needed (video)
 TestDriven Web Development with Python
 Dependency injection:
 How to write tests
 To cover:

 in an OS, how it works
 can be gleaned from Operating System videos

 understand what lies beneath the programming APIs you use
 can you implement them?

 Sedgewick  Suffix Arrays (video)
 Sedgewick  Substring Search (videos)
 Search pattern in text (video)
If you need more detail on this subject, see "String Matching" section in Additional Detail on Some Subjects
System Design, Scalability, Data Handling
 You can expect system design questions if you have 4+ years of experience.
 Scalability and System Design are very large topics with many topics and resources, since there is a lot to consider when designing a software/hardware system that can scale. Expect to spend quite a bit of time on this.
 Considerations from Yegge:
 scalability
 Distill large data sets to single values
 Transform one data set to another
 Handling obscenely large amounts of data
 system design
 features sets
 interfaces
 class hierarchies
 designing a system under certain constraints
 simplicity and robustness
 tradeoffs
 performance analysis and optimization
 scalability
 START HERE: System Design from HiredInTech
 How Do I Prepare To Answer Design Questions In A Technical Inverview?
 8 Things You Need to Know Before a System Design Interview
 Algorithm design
 Database Normalization  1NF, 2NF, 3NF and 4NF (video)
 System Design Interview  There are a lot of resources in this one. Look through the articles and examples. I put some of them below.
 How to ace a systems design interview
 Numbers Everyone Should Know
 How long does it take to make a context switch?
 Transactions Across Datacenters (video)
 A plain English introduction to CAP Theorem
 Paxos Consensus algorithm:
 Consistent Hashing
 NoSQL Patterns

Scalability:
 Great overview (video)
 Short series:
 Scalable Web Architecture and Distributed Systems
 Fallacies of Distributed Computing Explained
 Pragmatic Programming Techniques
 Jeff Dean  Building Software Systems At Google and Lessons Learned (video)
 Introduction to Architecting Systems for Scale
 Scaling mobile games to a global audience using App Engine and Cloud Datastore (video)
 How Google Does PlanetScale Engineering for PlanetScale Infra (video)
 The Importance of Algorithms
 Sharding
 Scale at Facebook (2009)
 Scale at Facebook (2012), "Building for a Billion Users" (video)
 Engineering for the Long Game  Astrid Atkinson Keynote(video)
 7 Years Of YouTube Scalability Lessons In 30 Minutes
 How PayPal Scaled To Billions Of Transactions Daily Using Just 8VMs
 How to Remove Duplicates in Large Datasets
 A look inside Etsy's scale and engineering culture with Jon Cowie (video)
 What Led Amazon to its Own Microservices Architecture
 To Compress Or Not To Compress, That Was Uber's Question
 Asyncio Tarantool Queue, Get In The Queue
 When Should Approximate Query Processing Be Used?
 Google's Transition From Single Datacenter, To Failover, To A Native Multihomed Architecture
 Spanner
 Egnyte Architecture: Lessons Learned In Building And Scaling A Multi Petabyte Distributed System
 Machine Learning Driven Programming: A New Programming For A New World
 The Image Optimization Technology That Serves Millions Of Requests Per Day
 A Patreon Architecture Short
 Tinder: How Does One Of The Largest Recommendation Engines Decide Who You'll See Next?
 Design Of A Modern Cache
 Live Video Streaming At Facebook Scale
 A Beginner's Guide To Scaling To 11 Million+ Users On Amazon's AWS
 How Does The Use Of Docker Effect Latency?
 Does AMP Counter An Existential Threat To Google?
 A 360 Degree View Of The Entire Netflix Stack
 Latency Is Everywhere And It Costs You Sales  How To Crush It
 Serverless (very long, just need the gist)
 What Powers Instagram: Hundreds of Instances, Dozens of Technologies
 Cinchcast Architecture  Producing 1,500 Hours Of Audio Every Day
 Justin.Tv's Live Video Broadcasting Architecture
 Playfish's Social Gaming Architecture  50 Million Monthly Users And Growing
 TripAdvisor Architecture  40M Visitors, 200M Dynamic Page Views, 30TB Data
 PlentyOfFish Architecture
 Salesforce Architecture  How They Handle 1.3 Billion Transactions A Day
 ESPN's Architecture At Scale  Operating At 100,000 Duh Nuh Nuhs Per Second
 See "Messaging, Serialization, and Queueing Systems" way below for info on some of the technologies that can glue services together
 Twitter:
 For even more, see "Mining Massive Datasets" video series in the Video Series section.

Practicing the system design process: Here are some ideas to try working through on paper, each with some documentation on how it was handled in the real world:
 review: System Design from HiredInTech
 cheat sheet
 flow:
 Understand the problem and scope:
 define the use cases, with interviewer's help
 suggest additional features
 remove items that interviewer deems out of scope
 assume high availability is required, add as a use case
 Think about constraints:
 ask how many requests per month
 ask how many requests per second (they may volunteer it or make you do the math)
 estimate reads vs. writes percentage
 keep 80/20 rule in mind when estimating
 how much data written per second
 total storage required over 5 years
 how much data read per second
 Abstract design:
 layers (service, data, caching)
 infrastructure: load balancing, messaging
 rough overview of any key algorithm that drives the service
 consider bottlenecks and determine solutions
 Understand the problem and scope:
 Exercises:
 Design a CDN network: old article
 Design a random unique ID generation system
 Design an online multiplayer card game
 Design a keyvalue database
 Design a function to return the top k requests during past time interval
 Design a picture sharing system
 Design a recommendation system
 Design a URLshortener system: copied from above
 Design a cache system
Final Review
This section will have shorter videos that can you watch pretty quickly to review most of the important concepts.
It's nice if you want a refresher often.
 Series of 23 minutes short subject videos (23 videos)
 Series of 25 minutes short subject videos  Michael Sambol (18 videos):
 Sedgewick Videos  Algorithms I
 Sedgewick Videos  Algorithms II
Coding Question Practice
Now that you know all the computer science topics above, it's time to practice answering coding problems.
Coding question practice is not about memorizing answers to programming problems.
Why you need to practice doing programming problems:
 problem recognition, and where the right data structures and algorithms fit in
 gathering requirements for the problem
 talking your way through the problem like you will in the interview
 coding on a whiteboard or paper, not a computer
 coming up with time and space complexity for your solutions
 testing your solutions
There is a great intro for methodical, communicative problem solving in an interview. You'll get this from the programming interview books, too, but I found this outstanding:
No whiteboard at home? That makes sense. I'm a weirdo and have a big whiteboard. Instead of a whiteboard, pick up a large drawing pad from an art store. You can sit on the couch and practice. This is my "sofa whiteboard". I added the pen in the photo for scale.
Supplemental:
 Mathematics for Topcoders
 Dynamic Programming – From Novice to Advanced
 MIT Interview Materials
 Exercises for getting better at a given language
Read as a review and problem recognition

Algorithm Design Manual (Skiena)
 This book has 2 parts:
 class textbook on data structures and algorithms
 pros:
 is a good review as any algorithms textbook would be
 nice stories from his experiences solving problems in industry and academia
 code examples in C
 cons:
 can be as dense or impenetrable as CLRS, and in some cases, CLRS may be a better alternative for some subjects
 chapters 7, 8, 9 can be painful to try to follow, as some items are not explained well or require more brain than I have
 don't get me wrong: I like Skiena, his teaching style, and mannerisms, but I may not be Stony Brook material.
 pros:
 algorithm catalog:
 this is the real reason you buy this book.
 about to get to this part. Will update here once I've made my way through it.
 class textbook on data structures and algorithms
 To quote Yegge: "More than any other book it helped me understand just how astonishingly commonplace (and important) graph problems are – they should be part of every working programmer's toolkit. The book also covers basic data structures and sorting algorithms, which is a nice bonus. But the gold mine is the second half of the book, which is a sort of encyclopedia of 1pagers on zillions of useful problems and various ways to solve them, without too much detail. Almost every 1pager has a simple picture, making it easy to remember. This is a great way to learn how to identify hundreds of problem types."
 Can rent it on kindle
 Half.com is a great resource for textbooks at good prices.
 Answers:
 Errata
 This book has 2 parts:
Read and Do Programming Problems (in this order):

Programming Interviews Exposed: Secrets to Landing Your Next Job, 2nd Edition
 recommended in Google candidate coaching

Cracking the Coding Interview, 6th Edition
 recommended on the Google Careers site
 If you see people reference "The Google Resume", it was a book replaced by "Cracking the Coding Interview".
If you have time

Programming Pearls
 The first couple of chapters present clever solutions to programming problems (some very old using data tape) but that is just an intro. This a guidebook on program design and architecture, much like Code Complete, but much shorter.

Grokking Algorithms
 This is a great book for review of CS concepts, and a very quick read.
 Did not have as much Python code as I had hoped for, but has a great chapter on dynamic programming, so I worked through that and finally got the concept.

Write Great Code: Volume 1: Understanding the Machine
 The book was published in 2004, and is a bit outdated, but it's a terrific resource for understanding a computer.
 The author invented HLA, so take mentions and examples in HLA with a grain of salt. Not widely used, but decent examples of what assembly looks like.
 These chapters are worth the read to give you a nice foundation:
 Chapter 2  Numeric Representation
 Chapter 3  Binary Arithmetic and Bit Operations
 Chapter 4  FloatingPoint Representation
 Chapter 5  Character Representation
 Chapter 6  Memory Organization and Access
 Chapter 7  Composite Data Types and Memory Objects
 Chapter 9  CPU Architecture
 Chapter 10  Instruction Set Architecture
 Chapter 11  Memory Architecture and Organization
 For a richer, more uptodate (2011), but longer treatment, pick up Computer Architecture, Fifth Edition: A Quantitative Approach

Elements of Programming Interviews
 all code is in C++, if you're looking to use C++ in your interview
 a good book on problem solving in general.
Perhaps

Introduction to Algorithms
 Important: Reading this book will only have limited value. This book is a great review of algorithms and data structures, but won't teach you how to write good code. You have to be able to code a decent solution efficiently.
 To quote Yegge: "But if you want to come into your interviews prepped, then consider deferring your application until you've made your way through that book."
 Half.com is a great resource for textbooks at good prices.
 aka CLR, sometimes CLRS, because Stein was late to the game
Removed

"Algorithms and Programming: Problems and Solutions" by Shen A fine book, but after working through problems on several pages I got frustrated with the Pascal, do while loops, 1indexed arrays, and unclear postcondition satisfaction results.
 Would rather spend time on coding problems from another book or online coding problems.
Coding exercises/challenges
Once you've learned your brains out, put those brains to work. Take coding challenges every day, as many as you can.
Challenge sites:
 LeetCode
 TopCoder
 Project Euler (mathfocused)
 Codewars
 HackerRank
 Codility
 InterviewCake
 InterviewBit
Maybe:
Once you're closer to the interview
 Cracking The Coding Interview Set 2 (videos):
Your Resume
 Ten Tips for a (Slightly) Less Awful Resume
 See Resume prep items in Cracking The Coding Interview and back of Programming Interviews Exposed
Be thinking of for when the interview comes
Think of about 20 interview questions you'll get, along with the lines of the items below. Have 23 answers for each. Have a story, not just data, about something you accomplished.
 Why do you want this job?
 What's a tough problem you've solved?
 Biggest challenges faced?
 Best/worst designs seen?
 Ideas for improving an existing Google product.
 How do you work best, as an individual and as part of a team?
 Which of your skills or experiences would be assets in the role and why?
 What did you most enjoy at [job x / project y]?
 What was the biggest challenge you faced at [job x / project y]?
 What was the hardest bug you faced at [job x / project y]?
 What did you learn at [job x / project y]?
 What would you have done better at [job x / project y]?
Have questions for the interviewer
Some of mine (I already may know answer to but want their opinion or team perspective):
 How large is your team?
 What does your dev cycle look like? Do you do waterfall/sprints/agile?
 Are rushes to deadlines common? Or is there flexibility?
 How are decisions made in your team?
 How many meetings do you have per week?
 Do you feel your work environment helps you concentrate?
 What are you working on?
 What do you like about it?
 What is the work life like?
Once You've Got The Job
Congratulations!
Keep learning.
You're never really done.
*****************************************************************************************************
*****************************************************************************************************
Everything below this point is optional. These are my recommendations, not Google's.
By studying these, you'll get greater exposure to more CS concepts, and will be better prepared for
any software engineering job. You'll be a much more wellrounded software engineer.
*****************************************************************************************************
*****************************************************************************************************
Additional Books

The Unix Programming Environment
 an oldie but a goodie

The Linux Command Line: A Complete Introduction
 a modern option
 TCP/IP Illustrated Series

Head First Design Patterns
 a gentle introduction to design patterns

Design Patterns: Elements of Reusable ObjectOriented Software
 aka the "Gang Of Four" book, or GOF
 the canonical design patterns book
 Site Reliability Engineering
 UNIX and Linux System Administration Handbook, 4th Edition
Additional Learning




 Big And Little Endian
 Big Endian Vs Little Endian (video)

Big And Little Endian Inside/Out (video)
 Very technical talk for kernel devs. Don't worry if most is over your head.
 The first half is enough.

 suggested by Yegge, from an old Amazon recruiting post: Familiarize yourself with a unixbased code editor
 vi(m):
 emacs:


 Khan Academy
 more about Markov processes:
 See more in MIT 6.050J Information and Entropy series below.

 Intro
 Parity
 Hamming Code:
 Error Checking

 also see videos below
 make sure to watch information theory videos first
 Information Theory, Claude Shannon, Entropy, Redundancy, Data Compression & Bits (video)

 also see videos below
 make sure to watch information theory videos first
 Khan Academy Series
 Cryptography: Hash Functions
 Cryptography: Encryption

 make sure to watch information theory videos first
 Computerphile (videos):
 Compressor Head videos
 (optional) Google Developers Live: GZIP is not enough!

 if you have networking experience or want to be a systems engineer, expect questions
 otherwise, this is just good to know
 Khan Academy
 UDP and TCP: Comparison of Transport Protocols
 TCP/IP and the OSI Model Explained!
 Packet Transmission across the Internet. Networking & TCP/IP tutorial.
 HTTP
 SSL and HTTPS
 SSL/TLS
 HTTP 2.0
 Video Series (21 videos)
 Subnetting Demystified  Part 5 CIDR Notation






 Given a Bloom filter with m bits and k hashing functions, both insertion and membership testing are O(k)
 Bloom Filters
 Bloom Filters  Mining of Massive Datasets  Stanford University
 Tutorial
 How To Write A Bloom Filter App


 used to determine the similarity of documents
 the opposite of MD5 or SHA which are used to determine if 2 documents/strings are exactly the same.
 Simhashing (hopefully) made simple



 Note there are different kinds of tries. Some have prefixes, some don't, and some use string instead of bits to track the path.
 I read through code, but will not implement.
 Sedgewick  Tries (3 videos)
 Notes on Data Structures and Programming Techniques
 Short course videos:
 The Trie: A Neglected Data Structure
 TopCoder  Using Tries
 Stanford Lecture (real world use case) (video)
 MIT, Advanced Data Structures, Strings (can get pretty obscure about halfway through)

 Know least one type of balanced binary tree (and know how it's implemented):
 "Among balanced search trees, AVL and 2/3 trees are now passé, and redblack trees seem to be more popular. A particularly interesting selforganizing data structure is the splay tree, which uses rotations to move any accessed key to the root."  Skiena
 Of these, I chose to implement a splay tree. From what I've read, you won't implement a
balanced search tree in your interview. But I wanted exposure to coding one up
and let's face it, splay trees are the bee's knees. I did read a lot of redblack tree code.
 splay tree: insert, search, delete functions If you end up implementing red/black tree try just these:
 search and insertion functions, skipping delete
 I want to learn more about BTree since it's used so widely with very large data sets.

AVL trees
 In practice: From what I can tell, these aren't used much in practice, but I could see where they would be: The AVL tree is another structure supporting O(log n) search, insertion, and removal. It is more rigidly balanced than red–black trees, leading to slower insertion and removal but faster retrieval. This makes it attractive for data structures that may be built once and loaded without reconstruction, such as language dictionaries (or program dictionaries, such as the opcodes of an assembler or interpreter).
 MIT AVL Trees / AVL Sort (video)
 AVL Trees (video)
 AVL Tree Implementation (video)
 Split And Merge

Splay trees
 In practice: Splay trees are typically used in the implementation of caches, memory allocators, routers, garbage collectors, data compression, ropes (replacement of string used for long text strings), in Windows NT (in the virtual memory, networking and file system code) etc.
 CS 61B: Splay Trees (video)

MIT Lecture: Splay Trees:
 Gets very mathy, but watch the last 10 minutes for sure.
 Video

Red/black trees
 these are a translation of a 23 tree (see below)
 In practice: Red–black trees offer worstcase guarantees for insertion time, deletion time, and search time. Not only does this make them valuable in timesensitive applications such as realtime applications, but it makes them valuable building blocks in other data structures which provide worstcase guarantees; for example, many data structures used in computational geometry can be based on red–black trees, and the Completely Fair Scheduler used in current Linux kernels uses red–black trees. In the version 8 of Java, the Collection HashMap has been modified such that instead of using a LinkedList to store identical elements with poor hashcodes, a RedBlack tree is used.
 Aduni  Algorithms  Lecture 4 (link jumps to starting point) (video)
 Aduni  Algorithms  Lecture 5 (video)
 Black Tree
 An Introduction To Binary Search And Red Black Tree

23 search trees
 In practice: 23 trees have faster inserts at the expense of slower searches (since height is more compared to AVL trees).
 You would use 23 tree very rarely because its implementation involves different types of nodes. Instead, people use Red Black trees.
 23Tree Intuition and Definition (video)
 Binary View of 23Tree
 23 Trees (student recitation) (video)

234 Trees (aka 24 trees)
 In practice: For every 24 tree, there are corresponding red–black trees with data elements in the same order. The insertion and deletion operations on 24 trees are also equivalent to colorflipping and rotations in red–black trees. This makes 24 trees an important tool for understanding the logic behind red–black trees, and this is why many introductory algorithm texts introduce 24 trees just before red–black trees, even though 24 trees are not often used in practice.
 CS 61B Lecture 26: Balanced Search Trees (video)
 Bottom Up 234Trees (video)
 Top Down 234Trees (video)

Nary (Kary, Mary) trees
 note: the N or K is the branching factor (max branches)
 binary trees are a 2ary tree, with branching factor = 2
 23 trees are 3ary
 KAry Tree

BTrees
 fun fact: it's a mystery, but the B could stand for Boeing, Balanced, or Bayer (coinventor)
 In Practice: BTrees are widely used in databases. Most modern filesystems use Btrees (or Variants). In addition to its use in databases, the Btree is also used in filesystems to allow quick random access to an arbitrary block in a particular file. The basic problem is turning the file block i address into a disk block (or perhaps to a cylinderheadsector) address.
 BTree
 Introduction to BTrees (video)
 BTree Definition and Insertion (video)
 BTree Deletion (video)
 MIT 6.851  Memory Hierarchy Models (video)  covers cacheoblivious BTrees, very interesting data structures  the first 37 minutes are very technical, may be skipped (B is block size, cache line size)

 great for finding number of points in a rectangle or higher dimension object
 a good fit for knearest neighbors
 Kd Trees (video)
 kNN Kd tree algorithm (video)

 "These are somewhat of a cult data structure"  Skiena
 Randomization: Skip Lists (video)
 For animations and a little more detail




 Combination of a binary search tree and a heap
 Treap
 Data Structures: Treaps explained (video)
 Applications in set operations



 see videos below

 Why ML?
 Google's Cloud Machine learning tools (video)
 Google Developers' Machine Learning Recipes (Scikit Learn & Tensorflow) (video)
 Tensorflow (video)
 Tensorflow Tutorials
 Practical Guide to implementing Neural Networks in Python (using Theano)
 Courses:

Great starter course: Machine Learning
 videos only
 see videos 1218 for a review of linear algebra (14 and 15 are duplicates)
 Neural Networks for Machine Learning
 Google's Deep Learning Nanodegree
 Google/Kaggle Machine Learning Engineer Nanodegree
 SelfDriving Car Engineer Nanodegree
 Metis Online Course ($99 for 2 months)

Great starter course: Machine Learning
 Resources:

Additional Detail on Some Subjects
I added these to reinforce some ideas already presented above, but didn't want to include them
above because it's just too much. It's easy to overdo it on a subject.
You want to get hired in this century, right?

UnionFind

More Dynamic Programming (videos)
 6.006: Dynamic Programming I: Fibonacci, Shortest Paths
 6.006: Dynamic Programming II: Text Justification, Blackjack
 6.006: DP III: Parenthesization, Edit Distance, Knapsack
 6.006: DP IV: Guitar Fingering, Tetris, Super Mario Bros.
 6.046: Dynamic Programming & Advanced DP
 6.046: Dynamic Programming: AllPairs Shortest Paths
 6.046: Dynamic Programming (student recitation)

Advanced Graph Processing (videos)

MIT Probability (mathy, and go slowly, which is good for mathy things) (videos):

String Matching
 RabinKarp (videos):
 KnuthMorrisPratt (KMP):
 Boyer–Moore string search algorithm

Coursera: Algorithms on Strings
 starts off great, but by the time it gets past KMP it gets more complicated than it needs to be
 nice explanation of tries
 can be skipped

Sorting
 Stanford lectures on sorting:
 Shai Simonson, Aduni.org:
 Steven Skiena lectures on sorting:
Video Series
Sit back and enjoy. "Netflix and skill" :P
List of individual Dynamic Programming problems (each is short)
Excellent  MIT Calculus Revisited: Single Variable Calculus
Computer Science 70, 001  Spring 2015  Discrete Mathematics and Probability Theory

CSE373  Analysis of Algorithms (25 videos)
UC Berkeley CS 152: Computer Architecture and Engineering (20 videos)
Carnegie Mellon  Computer Architecture Lectures (39 videos)
MIT 6.042J: Mathematics for Computer Science, Fall 2010 (25 videos)
MIT 6.050J: Information and Entropy, Spring 2008 (19 videos)