Hack Kosice challenge

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In the open part, you will connect multiple APIs in a creative way. In the closed part, you will be working on a similar but simplified task: forming the longest word chain by connecting words as in Domino.

Closed part

Given a list of words, your task is to find a string formed by chaining the highest number of words from the list. If there are multiple such strings, pick any single shortest string.

Two words can be chained together if a non-empty suffix of the first word is a prefix of the second word. For example, words camera and rainbow can be chained into string camerainbow. Each word can be used at most once when forming the chain (but this doesn’t mean that it must occur at most once in the final string).

Answer format: <number_of_words_used> <word_chain>

For example, for the words origami, sector, truck, or, the answer would be 3 sectorigami.

Words: rush, writer, grate, ignorant, cloudy, chicken, illness, useless, challenge, comfortable, noxious, desk, shade, error, great, zonked, flagrant, cute, plan, daughter, dare, giraffe, sack, airplane, aunt, men, blood, vase, cheap, obsolete, tomatoes, receipt, festive, screeching, moor, ingredients, great, skill, us, expansion, rex, lesson, one, nemo

Open part

Task: Combine multiple (at least 2) APIs in a creative way.


  1. learn new things
  2. demonstrate the power of APIs – show us the most obscure APIs that you found, and the ways how they can be combined to create surprising and funny solutions
  3. have fun


  1. Creativity – be inventive in how APIs can be combined
  2. Originality – the more unique your solution is, the better (i.e. don’t try to replicate something that already exists)
  3. Functionality – your solution doesn’t have to be useful, but it has to be functional
  4. (secondary criteria) Numbers of APIs used – the more APIs you combine in a creative way, the better

Note: your solution for this challenge does NOT need to be useful 🙂 The point is to be creative and have fun.


Examples of APIs that you can combine:

Examples of good projects

  • An Android app that records calls, then uses Google’s speech-to-text API to convert the recording into text, then uses the Natural Language API to extract information about dates/places, then uses the Calendar API to schedule events in the calendar (based on information mentioned in the phone call), and the Contacts API to also invite the email of the person that you called with.

  • A web app that will ask you to name a place (such as High Tatras, Slovakia), and tell you, how much older or younger will you be (according to the Theory of Relativity) if you travel to that place and back home, compared to staying at home (the difference in age would vary by very tiny amounts, smaller than picoseconds or so). You age slower or faster by moving across different gravitational fields, which normally happens when changing the altitude. The app would use the IP-API to get the approximate coordinates of your IP address at home, then Google’s Geocoding API to get the coordinates of your named place, then the Elevation API to get the elevation of both locations. Finally, it uses the time dilation formulas to calculate the predicted difference in ageing.

Examples of bad projects

  • A web app that tells you a random joke, by first randomly choosing an API from the list: JokeAPI, Jokes, Jokes One, Chuck Norris Database, icanhazdadjoke

    This is not a very creative combination of the APIs.

  • A web app that asks the user for a number, then uses the isEven API to print whether it’s even or odd

    Although the app is definitely humorous, there was zero innovativeness involved in combining multiple APIs in a creative way.