add contributing.md

README.md

@@ -11,7 +11,7 @@ Make a Python implementation of the library so that a Python programmer can lear
 
 Try to keep the interface and variable name consistent with the original book while not violating Python coding standards.
 
-## Usage
+## Install (WIP)
 
 `# pip install algs4`
 
@@ -76,3 +76,5 @@ This code is released under MIT.
 
 Issue reports and code fixes are welcome. please follow the same style as the code in the repository and add test for your
 code.
+
+[contributing guide](contributing.md)

contributing.md

@@ -0,0 +1,16 @@
+# Contributing
+
+## Python2 or Python3
+
+Please use **Python3** to develop and test your code. [Python2orPython3](https://wiki.python.org/moin/Python2orPython3)
+> In particular, instructors introducing Python to new programmers should consider teaching Python 3 first and then introducing the differences in Python 2 afterwards (if necessary), since Python 3 eliminates many quirks that can unnecessarily trip up beginning programmers trying to learn Python 2.
+
+
+## Development Process
+
+1. clone the project
+2. install it in development mode
+    ```
+    python setup.py develop
+    ```
+3. write code, test code, submit PR