Google Prep Material

Prep Material:

1. Step by Step Study Guide written by a new Googler who just went through the same interview process
2. Attached PDF - a few links, a video, and a few practice problems to cover technical phone screen basics
3. Helpful videos detailing the interview process: overview of the general hiring process, prepping for a technical interview, and a walk through of a coding problem
4. Refresher on your CS fundamentals:
1. Data Structures
2. Algorithms - with particular attention given to the "Searching and Sorting" section
3. Big O Notation - for a recap on BigO of these DS/Algo's
5. Strategies to answer interview questions - with particular attention to the sections 'Algorithm Design' and 'Systems Design'
6. Make sure and try some practice questions on sites like HackerRank, TopCoder, CodeChef, CareerCup.com, or projecteuler.net - handwrite your solutions!

Practice Tip! - Many candidates have found it helpful to practice writing code in a google doc. Then run test cases on your code and optimize it. Practice with the idea that the engineer who is interviewing you should be able to compile and run your code when you are finished.

Key topics to review: 

There is a lot of useful information in the document attached but you should make sure that you are prepared with complexity of algorithms and that you can implement a range of data structures using an array (especially hash maps and hash tables). 

Algorithms: BFS and DFS, and know the difference between inorder, postorder and preorder. http://www.geeksforgeeks.org/fundamentals-of-algorithms/ for more

Sorting: Know how to sort. Don't do bubble-sort. You should know the details of at least one n*log(n) sorting algorithm, preferably two (say, quick sort and merge sort). Merge sort can be highly useful in situations where quick sort is impractical, so take a look at it. See geeksforgeeks link above for sorting algorithms reference.

Big-O notation: also known as "the run time characteristic of an algorithm". You may want to refresh hash tables, heaps, binary trees, linked lists, depth-first search, recursion. http://bigocheatsheet.com/

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http://www.geeksforgeeks.org/data-structures/

Hashtables: Arguably the single most important data structure known to mankind. You absolutely should know how they work. Be able to implement one using only arrays in your favorite language, in about the space of one interview. 

Trees: Know about trees; basic tree construction, traversal and manipulation algorithms. Familiarize yourself with binary trees, n-ary trees, and trie-trees. Be familiar with at least one type of balanced binary tree, whether it's a red/black tree, a splay tree or an AVL tree, and know how it's implemented. Understand tree traversal 

Graphs: Graphs are really important at Google. There are 3 basic ways to represent a graph in memory (objects and pointers, matrix, and adjacency list); familiarize yourself with each representation and its pros & cons. You should know the basic graph traversal algorithms: breadth-first search and depth-first search. Know their computational complexity, their tradeoffs, and how to implement them in real code.

Additional reading if you're interested:

Quora: How should I prepare for my Google interview if I have one month left?