Update README.md

Author: Willy

README.md

@@ -15,3 +15,50 @@ Code is compatible Eclipse Oxigen, Gradle and Java 1.8. We'll keep this updated
 ```
 File > Import > Gradle > Gradle Project > Select the project forlder > done.
 ```
+
+## Data Structures
+The choice of data structure for a particular task depends on a few things.
+
+First, there is the shape of your data and the kinds of operations that you'll need to perform on it. If you want to look up objects by a key you need some kind of dictionary; if your data is hierarchical in nature you want a tree structure of some sort; if your data is sequential you want a stack or queue.
+
+Second, it matters what particular operations you'll be performing most, as certain data structures are optimized for certain actions. For example, if you often need to find the most important object in a collection, then a heap or priority queue is more optimal than a plain array.
+
+Most of the time using just the built-in Array, Dictionary, and Set types is sufficient, but sometimes you may want something more fancy...
+
+### Trees
+- Heap. A binary tree stored in an array, so it doesn't use pointers. Makes a great priority queue.
+Fibonacci Heap
+- B-Tree. A self-balancing search tree, in which nodes can have more than two children.
+
+### Hashing
+- Hash Table. Allows you to store and retrieve objects by a key. This is how the dictionary type is usually implemented.
+
+### Graphs
+- Graph.
+
+## Learn more!
+
+For more information, check out these great books:
+
+- [Introduction to Algorithms](https://mitpress.mit.edu/books/introduction-algorithms) by Cormen, Leiserson, Rivest, Stein
+- [The Algorithm Design Manual](http://www.algorist.com) by Skiena
+- [Elements of Programming Interviews](http://elementsofprogramminginterviews.com) by Aziz, Lee, Prakash
+- [Algorithms](http://www.cs.princeton.edu/~rs/) by Sedgewick
+- [Grokking Algorithms](https://www.manning.com/books/grokking-algorithms) by Aditya Bhargava
+
+The following books are available for free online:
+
+- [Algorithms](http://www.beust.com/algorithms.pdf) by Dasgupta, Papadimitriou, Vazirani
+- [Algorithms, Etc.](http://jeffe.cs.illinois.edu/teaching/algorithms/) by Erickson
+- [Algorithms + Data Structures = Programs](http://www.ethoberon.ethz.ch/WirthPubl/AD.pdf) by Wirth
+- Algorithms and Data Structures: The Basic Toolbox by Mehlhorn and Sanders
+- [Open Data Structures](http://opendatastructures.org) by Pat Morin
+- [Wikibooks: Algorithms and Implementations](https://en.wikibooks.org/wiki/Algorithm_Implementation)
+
+Other algorithm repositories:
+
+- [EKAlgorithms](https://github.com/EvgenyKarkan/EKAlgorithms). A great collection of algorithms in Objective-C.
+- [@lorentey](https://github.com/lorentey/). Production-quality Swift implementations of common algorithms and data structures.
+- [Rosetta Code](http://rosettacode.org). Implementations in pretty much any language you can think of.
+- [AlgorithmVisualizer](http://jasonpark.me/AlgorithmVisualizer/). Visualize algorithms on your browser.
+- [Swift Structures](https://github.com/waynewbishop/SwiftStructures) Data Structures with directions on how to use them [here](http://waynewbishop.com/swift)