vbachurin / spark-common-words Goto Github PK

#Introduction#

This exercise tests your ability to distinguish the signal from the noise. First, you will organize a random input into meaningful output. Second, you'll report on that output using software.

#Prerequisites#

Your answer will be written in any language that you prefere, and must meet the following requirements:

• It must run on *nix OS, and shouldn't require any unusual binaries or new software to run.

• Code should be covered by Unit/Integration tests

If you're a vagrant user, you can exactly replicate the box on which we'll test your answer by using this base box.

#The Randomness Beacon#

The National Institute of Standards and Technology broadcasts a signed, timestamped random bit sequence once a minute, every minute, and has since Unix epoch time 1378395540 (09/05/2013 11:39 a.m.). It's called the Randomness Beacon, and you're going to analyze it.

##Goal 1: Sampling Chaos##

The Randomness Beacon publishes a RESTful API, through which you can retrive any given minute's beacon value as 128 hexidecimal characters, as well as a variety of other authentication data. Your first goal is to summarize the beacon's emissions over arbitrary amounts of time.

That program should have the following characteristics:

1. Without additional arguments, it should retrieve the most recent event from the randomness beacon, and count the number of characters in the OutputValue the beacon returns. It should then print that output to standard out in comma-delimited format.

   For example, if the randomness beacon returned the string "01AF04F" for its OutputValue, your application should print:

    0,2
    1,1
    4,1
    A,1
    F,2
   

   The first value of any given line is a character. The second value is the number of times that value occurred in the OutputValue string.

2. When given optional --from and --to arguments, the application should output the character count over a span of beacon values using relative time. For example, if we provided the application the following arguments:

    $ summarize-beacon --from "3 months 1 day 1 hour ago" --to "1 month 1 hour ago"
   

   the application should parse the strings "3 months 1 day 1 hour ago" and "1 month 1 hour ago" into a time format the becaon's API can understand, and print the summed character count of all beacon values between those two times. The application should understand "month(s)," "day(s)", "hour(s)", and "minutes(s)", and should handle any combination of those values.

   Note that output is summed. For example, if the user enters --from and --to values that yield two beacon values, "B423AF" and "7352BA", the application should output the summed character counts of both values:

    2,2
    3,2
    4,1
    5,1
    7,1
    A,2
    B,2
    F,1
   

3. The application should error in a friendly way if a user enters a --from or --to time that predates the start of the beacon, Unix epoch time 1378395540.

A Quick Note: Don't feel obligated to solve this problem using just the some standard library. Part of engineering is knowing when to include 3rd party modules. In particular, if you know a good alternative to standard libraries, feel free to include it.

#Submitting Answers#

Submit solutions to this problem via Github pull requests.