adding new take-home exercises

Author: rohan-paul

Collection-of-TakeHome-Exercises/Android-take-home-exercise-1.md

@@ -0,0 +1,29 @@
+# Android Credit Card Input Exercise
+
+<img align="right" src="CreditCardInputExercise.gif" alt="A general idea of how it looks/works" title="A general idea of how it looks/works">
+
+### Requirements
+
+Basically, the Company asked to create an Android "screen" that would allow a user to enter and submit the
+following data from an American Express, Discover, MasterCard, or Visa credit card:
+
+- Credit card number
+- Expiration date (MM/YY format)
+- CVV security code
+- First name
+- Last name
+
+If any of the entered data was invalid, the user needed to be notified so the Company's Dev-Team could correct it.
+In addition to not having issues like empty fields or a badly-formed or expired expiration date,
+credit card data also had to meet these criteria to be considered valid:
+
+- Credit card numbers needed to be in valid American Express, Discover, MasterCard, or Visa format according
+  to the specs listed on https://www.cybersource.com/developers/getting_started/test_and_manage/best_practices/card_type_id/
+- Credit card numbers also needed to pass Luhn validation - see https://en.wikipedia.org/wiki/Luhn_algorithm
+- The CVV had to meet these criteria: https://www.cvvnumber.com/cvv.html
+- First and last names could only contain characters that were "alphabetical and spaces". _(It's true that many
+  people have hyphens in their names as well, but for this assignment I wasn't going to go past what was called
+  for in the specs, ditto for dealing with "international characters" even though I have one in my own first name.)_
+
+When the user submitted valid credit card data, the app should pop up an alert dialog notifying them that the
+payment was successful.