Challenges
Dive into our coding challenges to have fun and acquire new skills. Join us in chat to discuss!
Challenge #21: Knight's Sudoku
We are experimenting with more community authored Challenges, if you are interested in writing your own challenge, please head to the sandbox and post your idea there. This challenge was written by M--...
- 260 reputation score 260
Challenge #20: We all scream for Ice Cream! [COMPLETED]
Update on July 17: This challenge is now completed, thanks to everyone who participated! The correct output for each scenario is as follows: Scenario one: Chocolate: 25 tubs Vanilla: 28 tubs ...
- 101 reputation score 101
Challenge #19: In Other Words... [COMPLETED]
Update on June 17: This challenge is now closed, thanks to everyone who gave it a shot. The winners of this challenge are: André, Apfelvater, Daniel T, Fred Bill, Jannik S., joaocandre, Kane ...
- 1 reputation score 1
Challenge #18: Hidden in Plain Sight [COMPLETED]
Update on May 14, 2026: This challenge is now closed, thanks to everyone who participated. The winners of this challenge are: AKHolland, amance, Aravind K. B, Book, cknott, Daniel T, Dmitrii Bychenko, ...
- 2,306 reputation score 2306
Challenge #17: The Accurate Selection [COMPLETED]
Update on April 14, 2026: This challenge is now closed. Thanks to everyone who participated! The winners of this challenge, who solved all 10 selections, are: Atmo, cknott, keymasterr, Antoine, ...
- 101 reputation score 101
Challenge #16: Change is the only constant [COMPLETED]
Update on March 12, 2026: Thanks to everyone who participated in Challenge 16! The correct output is: 73, -1, 6, -1, 4, 2, -1, 5, 2, -1, 5, 2, 3, -1, 2, 4, 4, 2, 2, 2, 4, 4, 3, 2, 3, 2, 4, 3, 3, 4, 3, ...
- 101 reputation score 101
Challenge #15: Mystery Alphabet Decoder [COMPLETED]
Update on February 13, 2026: Thanks to everyone who participated in Challenge 15! The correct output for the alien alphabet is: ⪏⊚⊕⊟⊞⨙⊛∭↔⊠⊝৲⊣⊗⇲⊥⊢◉⊡⊤◴⚆⊜↪ 87 users got the right answer, out of 101 ...
- 101 reputation score 101
Challenge #14: Signal from Noise [COMPLETED]
Update on January 8, 2026: Huge thanks to everyone who participated in the challenge. The conditions for signal/noise were tricky, and we appreciate the careful implementations! The correct sum of the ...
- 189 reputation score 189
Challenge #13: Integer sorting in a grid [COMPLETED]
Update on October Dec 4: Huge thanks to everyone who participated in the challenge. The correct answer is that 45 of the sets were impossible to put into the grid. We received 70 responses from 68 ...
- 1 reputation score 1
Challenge #12: Spooky Halloween scene [COMPLETED]
Update, Nov 13: Thanks to all that participated and voted in this challenge! In terms of votes, top 3 entries were: 1st place: Phil with a spooky house scene 2nd place: Death-is-the-real-truth (...
- 1 reputation score 1
Challenge #11: Taco crawl optimization [COMPLETED]
Update on October 23: Huge thanks to everyone who participated in the challenge. The correct routing was [0,7,5,6,2,10,4] for 97 tastiness and 2.8945 tastiness/distance. 43 of the 53 entries provided ...
- 1 reputation score 1
Challenge #10: Road safety challenge (joint with Kaggle) [COMPLETED]
Update, Nov 1, 2025: The challenge is now complete. Thanks to those that participated. We'll review the entries and soon announce the users that receive the badge. Kaggle is a platform for Machine ...
- 1 reputation score 1
Challenge #9: Random Number Generator [COMPLETED]
Update: October 6, 2025: Thanks to everyone who participated in this challenge! It was very interesting to see the diverse approaches to random number generation. Congratulations to the following ...
- 1 reputation score 1
Challenge #8: Word ladder [COMPLETED]
Update, October 2, 2025: Appreciation to everyone who participated in this challenge! The correct length of the word ladders is as follows: [stone, money] [11] [bread, crumb] [11] [smile, giant] [11] ...
- 1 reputation score 1
Challenge #7: Pangram checker [COMPLETED]
Update, October 2, 2025: A HUGE thanks to everyone who participated in this challenge! The correct answer is: 819 Non-Pangrams, 132 Pangrams (non-perfect) and 49 Perfect-Pangrams. We are very ...
- 1 reputation score 1