Sliding window

The goal of the kata is to separate the generic solution to an interview question and make brain space for the actual business logic.


  • write the template for a sliding window solution

    • pay attention to the inclusive and exclusive values, if you don't +1 will eat your lunch

    • loop is 0 indexed

    • add an inner loop which looping depends on the values created by the outer loop

    • start from different values than 0

    • increase the step higher than 1

  • explain the O() notation of the solution

  • Testing:

    • be sure the sliding happens according to the expectations

    • use boundary value analysis to test it


  • what data can be simplified?

  • what data can be reworked to get further performance?

    • For example, a list looked up frequently or in every step can be reworked to HashMap for faster access.
  • Are there partial calculations that can be re-used?

  • Is there any opportunity to cache something?

  • If it is possible don't do any I/O operation in the loops, if you have to emphasize its problematic nature.