Improving Readme and adding Strategy pattern

README.md

@@ -1,5 +1,5 @@
 # Design and DesignPatterns
-####About
+#### About
 
 This is a repository which I use for learning design patterns. 
 This is formed as a notes with the book **Head First Design Patterns**
@@ -21,7 +21,24 @@ separate (*encpsulate*) them from what stays the same.
 
 # Design Patterns
 
-####Strategy Pattern
-Defines a family of algorithms, encapsulates each one and makes them interchangeable.
+#### Strategy Pattern
+>Defines a family of algorithms, encapsulates each one and makes them interchangeable.
 Strategy lets algorithm vary independently from clients that use it.
 
+Problem in hand?
+
+So *Duck* base class has implementations of a duck. Now the new requirement
+is to make ducks fly. 
+
+![Make ducks to fly](/assets/Strategy-problem.jpg "Make ducks fly")
+
+We can simply add fly method to base class - problem solved.
+But some rubber ducks can also fly now. so simply override to null?
+
+What if we have some other behaviour next? So **encapsulate** the changing behaviour,
+create a **composition** so that duck **Has-a** behaviour that can be changed during runtime.
+So behaviours are a *family of encapsulated algorithm that vary independently for each duck client.*    
+
+So the implementation looks like this.
+![Encapsulate Fly as algorithm so duck clients can use it independently](/assets/Strategy-solution.jpg 
+"Encapsulate Fly as algorithm so duck clients can use it independently")