This coding task is meant for those aspiring engineers who are applying for Wolt's Engineering Internships in 2019. Optionally you can send us a link to your Github profile (containing existing projects) or any example of your code in any format of your preference, and skip this exercise altogether. Find the details to apply here, deadline to apply is 17.2.2019.
Our courier partners are one of the main pillars of successful Wolt operations in 38 cities covering 14 countries (and growing fast!). Courier partners use Wolt's own mobile application that feeds them new tasks, allows reserving shifts, shows earnings and keeps everyone informed about the status of the city. The mobile app communicates with the backend where we have a pile of Scala, C++ and Python code constantly optimizing best delivery scenarios so that the operation will run smoothly and efficiently.
Wolt's delivery task is split into two parts: pickup and dropoff. A pickup task means driving to a restaurant, collecting the prepared food, putting it to a heat bag and then continuing with the next thing. A dropoff task covers the rest of the delivery - taking the food to a customer with a smile.
In this coding exercise we are going to focus on pickup tasks. When a customer buys food through Wolt, the first thing that will be done is to calculate a pickup time. A pickup time indicates how many minutes it will take for our courier partner to arrive to that specific restaurant. There are many factors to take into consideration:
- How many courier partners are available in the city
- How busy are courier partners
- How are courier partners located in relation to the restaurant
Obviously the busier the city is, the higher the pickup time. Very central areas of a town might be faster to reach, but they also often contain the most popular restaurants (biggest rush). On the other hand restaurants on outer areas of the town might have less orders, but they will require more travel time.
Your task is to help one of our courier operation managers to analyze pickup times. The courier operation manager has sent you a following message:
I would like understand what is the median pickup time for each restaurant between certain hours (e.g. 15-16). The data set of pickup times has been collected from Helsinki between 7.1. - 13.1.2019.
The first file contains all pickup locations (restaurants) in Helsinki and the second one all pickup times from that week.
I would like to have either an command line application or some kind of graphical user interface. Whichever you want to create. I need to be able to select the day and start / end hours when using the program.
The command line program could work something like this:
$ median_times Helsinki 07-01-19 19-20 mediantimes.csv
This command would calculate medians of pickup times for all locations (in Helsinki) between 19-20 on Monday 7.1 and store times to a CSV file (example below).
location_id,median_pickup_time
1,21
2,15
3,6
etc.
If you rather build a graphical user interface instead of the command line application, then here is my idea about that one.
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You can use any programming language and 3rd party libraries you want. However, we will really appreciate if you can write your solution with either Python, JavaScript or Scala (languages mostly used by Wolt).
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When you are ready, leave us an application here accompanied by your solution (stored in a GitHub repository or if in other format, send your code to [email protected])
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You need to build either an command line application or a graphical user interface (no need to do both). Examples above are just that, examples. Feel free to do a better design on how the input can be given to the program.
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The courier operation manager is only interested about median times between certain hours (without minutes). So there is no need to handle exact timestamps in this first MVP.
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We need to be able to test your program. So please provide good instructions how to get everything running smoothly.
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Everyone at Wolt loves clean code :)
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The courier operations manager probably wants to use your program also with other cities, so it might be a good idea to make the location of the data configurable.
If you have any questions about the task, don't hesitate to contact our Product Recruitment Manager at [email protected]
The data in this task is not real - coordinates do not point to real restaurants and pickup times have been fabricated. If you want to see how our system performs in real-life, impress us with your solution and come work with us!