101 Hack April'15

Speed! Accuracy! Efficiency!

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101 Hack is back with its 24th edition and this time it brings cool prizes! Passionate programmers will enjoy solving algorithmic challenges. It's all about speed, accuracy and efficiency: 5 challenges in 120 minutes. Every second counts!

This edition is sponsored by Cogito API, an award-winning product of Expert System USA Inc.


Winner gets a Pebble smartwatch. 2nd place gets wireless headphones by Voxoa. 3rd place gets a Hubscan quadcopter. Rank 4 through 20 get a cool HackerRank T-shirt.


  • Please refrain from discussing strategy during the contest.
  • Any case of code plagiarism will result in disqualification of both the users from the contest. We've a fairly good plagiarism detector that works at the opcode level.
  • You can code directly on our interface. We support 20 major languages. You can have a look at the environment in which we run your code. You can try out sample code given in Solve Me First to get familiar with I/O.
  • HackerRank admins decision will be final


  • Each challenge has a pre-determined score.
  • Each submission for each problem will be scored, based on number of testcases it passes.
  • The total score of any participant is the sum of their maximum scores of each of the attempted problems.
  • Participants are ranked according to their scores. Cumulative time taken to solve the challenge is used as a tie-breaker.


1st place: Pebble watch
2nd place: wireless headphones by Voxoa
3rd place: Hubscan quadcopter
4-20 will each get a HackerRank T-shirt


Cogito API is a text analytics API based on Cogito, the patented and award-winning technology developed by Expert System, the leading semantic intelligence company. Cogito API understands the meaning of words in context, and processes unstructured content at the speed of cutting edge technology.

Cogito API combines the power of natural language processing with semantic technology to analyze large volumes of content, in a ready to integrate and “made for developers” REST API.