January 29th, 2017

Python Programming Challenge – first to five

others, Programing, Python, by admin.

We’ve partnered with our friends at Interview Cake to bring you a programming challenge to test your logic skills and abilities.

Updated 10/16/2015: Added additional challenges – cheers!

The Challenge

  1. There are two players.
  2. Each player writes a number, hidden from the other player. It can be any integer 1 or greater.
  3. The players reveal their numbers.
  4. Whoever chose the lower number gets 1 point, unless the lower number is lower by only 1, then the player with the higher number gets 2 points.
  5. If they both chose the same number, neither player gets a point.
  6. This repeats, and the game ends when one player has 5 points.

The challenge is to write a script to play this game. Knowing the rules and all your opponent’s previous numbers, can you program a strategy? (And, no – return random.randint(1, 3) is not a strategy.) You should really try playing this first with your friends – you’ll see there’s a deep human element to predicting your opponent’s choice.

Is it possible to program a strong strategy?

Want to make the strategy a bit more interesting? Add an additional constraint to the challenge so that players can only use each number once. The first ten working submissions get a free copy of Real Python! (still open to submissions)

The Prizes

Need some motivation? We’ll be giving out prizes to the strategies that perform the best:

Although the challenge is officially over (results) you can still partake! First, see if you can beat the current winner to receive $20 off of Real Python. Second, create a web application with Flask that (a) makes it easy to add a new strategy and then (b) runs a given strategy against all the other strategies.


The grading is simple: We’ll run each strategy through the random number generator 100 times as a first screen – return random.randrange(1, 10). The strategies that beat the generator we’ll then be ran against one other in a round robin format to determine the overall winners. Be sure to test your code out in the game runner before submitting.

To submit your script, just email us a link to a secret Gist – info (at) realpython (dot) com. Good luck!

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