Update README.md

Author: Li Yin

README.md

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 Partially open sourced content from my book serie, *The Comprehensive Coding Interview Guide*. Currently two parts and will be hopefully published as two books:
 - The Data Structures and Algorithms Concepts
 - The LeetCode Problem Catalog
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 The book serie uses Python 3 as programming language, and LeetCode Problems as examples. The advantages of doing so are obvious:
 
 (1) Python is becoming the most popular language in the age of AI, and there are not many interview guide books using Python.
 
 (2) Using LeetCode Problems because first they are real coding interview questions; second, with the online judge system, it is easier for learners to practice online and with the support of the community, it makes the learning process more fun.
 
+## The Purpose of *The Comprehensive Coding Interview Guide*
+My purpose here is to offer any person who is interested with getting hands dirty with algorithms and coding a practical and strict manual to guide them through this process. The content is supposed to not only correct (that the code and algorithms work) and catchy  but also discreet (i.e , to know why it works, when it works, and how it works but not as theoretical as the *Introduction to Algorithms*).
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 ## The Data Structures and Algorithms Concepts
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+## Feedback
+If you like the example chapters that I put here, please leave your comment here. This book comes with a lot of hard work --personally, I paused my PhD program for a semester to focus on. Therefore, your comment is important to lead to the publication of the work. 
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+If you have ideas to imporove the book, about formating, more contents, or correct the erros are also very welcome too. 
+## Cooperation