Patterns, Strings & Array Tutorials & Practice (FREE)😱

Choosing a career path leading towards backend development is like moving into the flourishing field of web development? 💻As a back-end developer, your tasks will include building and maintaining the technology needed to power the components enabling the user-facing side of the website to exist. The back end code you create will add utility to everything the front-end developer creates. Aside from making web applications functional, backend developers👩‍💻 are also responsible for optimizing the application for speed and efficiency.

In short, as lucrative as a career in backend development seems, the role requires knowledge of bulk of skill sets. It is therefore crucial to be extremely thorough with the fundamentals of the course. This free tutorial includes a refresher to jog your memory on Patterns, Strings & Arrays - some of the most basic foundation concepts required to master in for any aspirant of Backend Development.

As part of Skillenza initiative SkillDojo, your one-stop solution for learning, upskilling and advancing towards your dream career, we have excellent guides for you to take your skillset up a notch.👩‍💻

Take advantage of these preparatory material designed especially for you to help you crack any coding interview.
(Please check under the Resources tab to access all the resources.)

For practice:

There are 2 stages of competitive programming practice tests.
We recommend that you go through the resources before you take the self-assessment tests to gauge your current capability.
Just click on the Register button and start your test.
Once you’ve finished with your self-assessment, you will be able to see your score.
If you are not satisfied with it, we suggest that you go through the study material again.

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A bit more about competitive programming (CP)

What is competitive programming?

It’s a programming challenge with test cases and constraints. The programs are command-line ones.
The test case is a set of two files viz. Input and output. The input is directed into the program through STDIN and the output from the program is compared with the expected output. We additionally support reading from an extracted zipped folder also.

What is the scoring scheme for competitive programming?

The dashboard provides two modes viz. test and submit. Test runs your code against sample/public test cases. Submit runs against hidden/private ones. Only sample test cases and their elaborate run results are made available. We also show a line by line comparison with the expected output. For the hidden/private test cases, only we only show the exit code, passed status, time consumption, memory consumption and score. We expect users to take cues from these values.

Both the public and private test cases use the same parameters/constants (check below for information on the parameters). It’s just that using the test button will award a 0 score for the leader-board irrespective of whether or not the code passed the public test cases. It’s for debugging only.

The score is entirely dependant on the output values from the test run viz. execution time, memory consumed and program size in characters. Time elapsed since the start of the test is not a parameter as of now but we might introduce it in the future. The code judging system lets the setter set weight-ages (non-negative weight-ages to the three parameters). If the metric is only performance, a setter can set a positive weight for time and have the memory and size as zero.

The formula for a single test case given correct output is

memory_weight*(1 - memory/memory_max) + time_weight*(1 - time/time_max) + size_weight*(1 - size/size_max)

This is summed across all the test cases (each test case also has a positive weight-age) and finally normalised to 100.

Is it possible to get 100% in any test case?

Yes. If it’s a time-weighted one, because of the precision of the system, one can complete execution in 0s.