Country Codes is one of the five questions in the HackerRank SQL (Basic) certification test. The join is simple. Most people who fail it get the string joining wrong, because MySQL handles it ...

This is one of the questions in the HackerRank SQL (Intermediate) certification test. It was one of the two I got when I took the test in June 2022. The query below is tested on MySQL 8.0 and 5.7.

This is the shortest question in the Python (Basic) pool. It checks one thing: do you know how to write a function that takes any number of arguments. You write a function called avg. HackerRank reads ...

A multiset is a set that can hold the same value more than once. This question checks two dunder methods, __contains__ and __len__, and whether you handle duplicates and missing values correctly.

A string question with two small steps. Most people who fail it do one of the steps on the wrong thing: they reverse the letters instead of the words. You get a sentence made of words separated by ...

This question tests one dunder method, __str__. The logic is trivial. What fails people is a single wrong character in the output sentence.

One of the easier questions in the pool. If you know sets and string iteration, it takes five minutes. The marks are lost on output order and on small typos. The input string contains only lowercase ...

Customer Spending looks like the easiest question in the HackerRank SQL (Intermediate) test. The logic is short. What trips people up is the output format: the amount has to show 6 decimal places, and ...

This was the other question I got in my attempt. It is a 2D grid question, and the whole difficulty is in handling the borders and ties correctly. You get a grid of integers with n rows and m columns.

Student Advisor is one of the five questions in the HackerRank SQL (Basic) certification test. It looks like a copy of the other join questions, but it has two salary limits, one for each gender, and ...

A small classes question. It checks whether you can store state on an object and make len() work on your own class. The same item can be added more than once, and every add call counts. There are at ...

Profitable Stocks is one of the five questions in the HackerRank SQL (Basic) certification test. It is short. The two things to get right are the comparison and the sort. There is one table of today’s ...