add readme for prototype pattern

README.md

@@ -47,7 +47,8 @@ Also if you know another algorithm or data structure that was not in here, creat
  - [Creational patterns](./design_patterns/creational_patterns)
  - [Abstract factory pattern](./design_patterns/creational_patterns/abstract_factory_pattern)
  - [Builder pattern](./design_patterns/creational_patterns/builder_pattern)
- - [Builder pattern](./design_patterns/creational_patterns/factory_method)
+ - [Factory pattern](./design_patterns/creational_patterns/factory_method)
+ - [Prototype](./design_patterns/creational_patterns/prototype)
 
 # Contributing
 

design_patterns/creational_patterns/prototype/README.md

@@ -0,0 +1,16 @@
+# Prototype
+
+![prototype](https://upload.wikimedia.org/wikipedia/commons/1/14/Prototype_UML.svg)
+
+[read more in wikipedia](https://en.wikipedia.org/wiki/Prototype_pattern)
+
+The prototype pattern is a creational design pattern in software development. It is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects. This pattern is used to:
+
+- avoid subclasses of an object creator in the client application, like the factory method pattern does.
+- avoid the inherent cost of creating a new object in the standard way (e.g., using the 'new' keyword) when it is prohibitively expensive for a given application.
+
+To implement the pattern, declare an abstract base class that specifies a pure virtual clone() method. Any class that needs a "polymorphic constructor" capability derives itself from the abstract base class, and implements the clone() operation.
+
+The client, instead of writing code that invokes the "new" operator on a hard-coded class name, calls the clone() method on the prototype, calls a factory method with a parameter designating the particular concrete derived class desired, or invokes the clone() method through some mechanism provided by another design pattern.
+
+The mitotic division of a cell — resulting in two identical cells — is an example of a prototype that plays an active role in copying itself and thus, demonstrates the Prototype pattern. When a cell splits, two cells of identical genotype result. In other words, the cell clones itself.