Tips for tasks on Codility

The post collects preparation tips for Codility tasks. It says the platform measures programming ability with a few timed problems that must meet running time and space constraints, and it advises practicing the demo, reviewing Big O, sorting, hash tables, and using a familiar language and IDE.

It also recommends reading the prompt carefully, identifying the problem type, drafting an initial solution that fits the constraints, writing the main logic before edge cases, and testing large values and boundary positions. Unit tests, a quiet workspace, and local tools are presented as ways to save time and avoid mistakes.

Reading notes

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• Codility is described as a tool for measuring programming capabilities with three selected tasks under time and space constraints.
• The demo is presented as a way to get used to the platform and the time pressure.
• The author recommends refreshing Big O notation, simple sorting algorithms, hash tables, and hash functions.
• Knowing the standard libraries of the chosen language is presented as a way to avoid reinventing common solutions.
• Unit testing is recommended on Codility, with attention to cases that return true, false, arrays, numbers, or -1.
• A quiet workplace with fewer distractions is suggested before starting the test.
• The task statement should be read carefully to avoid misunderstanding the problem.
• The post quotes a list of problem-solving approaches from Algorithms for Interviews, including divide-and-conquer, dynamic programming, case analysis, generalization, data structures, iterative refinement, small examples, reduction, graph modeling, equations, auxiliary elements, variation, parallelism, caching, and symmetry.
• The author advises forming an initial solution that satisfies the complexity constraints, even if it is not final.
• The main algorithm should be written first, then edge cases should be handled.
• Edge cases include large numbers, arithmetic overflow, and items at the start or end of the input.
• The author suggests using a local IDE instead of Codility’s web IDE because of lag and lack of autocompletion.
• The post ends by listing resources such as Algorithms for Interviews, The Algorithm Design Manual, Udacity, and Coursera.