Can you imagine the hardest interview ever ? Here I will try to help you understand how to handle the interview in the well known Australian start-up – Can>a .

The first stage is a project or on site interview. I have chosen the project because there is no time pressure and you may solve the problem at your own pace. If you are not enough self confident to hack the task on site, I recommend you the same approach.

Continue reading “Can>a fail”

TrapAdvisor part 2 – BigData solution

This article is the continuation of one of my previous 9512425840. It is a real task I got during one of job interviews for a Java Daveloper position. This time I will focus not only on possible Java and Scala solutions but I will also present BigData solution. Please stay tuned!

The task you are going to solve is the implementation for the following interface:

public interface Solution {

     * Find number of pairs in a given array {@param a} which sum up to the defined number {@param n}
     * @param a array of integer >= 0
     * @param n sum to which numbers should sum up
     * @return number of pairs, we count only combinations(order does not matter) e.g for
     * the array {2,3,3,3,4} and n = 6 we have unique pairs {2,3},{2,4},{3,3},{3,4} and only pairs
     * {3,3},{2,4} sums up to n = 6 so we return 2. Please notice that we do not take into account repetitions like
     * (3,3) and (3,3) or (2,3) and (3,2)
    long find(int a[], int n);

Continue reading “TrapAdvisor part 2 – BigData solution”

I am just tyro at HackerRank

HackerRank tests can be challenging not only because you have very limited time to write the implementation but also because very often you are not allowed to add new imports to the Solution class. Unlike Scala, Java does not allow you to add imports inside a method.

Next time if you ask your candidates about Java 8 skills please remember to add these two important packages

import java.util.function

These are fundamental packages for Java 8 !


HackerRank for me is the same what is false positive test for developers. You may feel secure because you wrote plenty of passing unit tests which covers 100% of your code. Likewise, being an employer because your candidates passed HackerRank tests and achieved the highest score. Unfortunately, like faulty tests HackerRank gives companies only empty promises. You may find many articles about recruiters who give tests away to their candidates just in order to benefit from their employment. Even if companies recruit the candidates on their own it is still highly doubtful method of recruitment. HackerRank tasks in most cases test only imperative skills of programmers in other words if-else-loop error prone code skills.  So let me ask you a question – which code do you find more understandable and want your future programmers would write for you ?

Solution 1:

int result = 0;
for( int i = 0; i < 10; i++ ){ 
   result += i; 
return result;

Solution 2:

return IntStream.range(0,10).sum(); 

If your answer is 1 keep going sending HackerRank tests to your candidates. Otherwise, rethink your recruitment process.

Unfortunately, it is a common practice in Australia to ask interviewees to solve HackerRank tests before proper interview. Therefore, I decided to publish series of articles about solving real life tasks, I got during my job interviews for a Java developer position in Sydney. Not only will it help other candidates to understand type of questions they may face but also show them proper way to solve that tasks. That means that for each task I will prepare few possible solutions, one for recruiters who look for “developers”  and other for Developers who are interested in developing their skills.

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