The recruitment process began with a LinkedIn message from a recruiter.

Following this, I had a brief phone interview. The questions covered topics such as "What technologies do you want to learn?" and "Why do you want to leave your current job?"

Some time later, the recruiter contacted me again and asked me to apply through Yandex's online application form. To proceed, I had to complete an assignment.

After submitting the assignment, we arranged a Skype interview. During this interview, I was asked more thoroughly about my favorite languages, technologies, and overall experience in software development. I then spent an hour and a half solving a tricky autogenerated assignment in an online editor and answering questions verbally. The assignment included questions about JavaScript, CSS, and HTML.

The following week, I had another round of Skype interviews conducted by members of one of the teams.

Two days later, I attended a 3-hour interview at Yandex HQ. The interview was lengthy because several teams had expressed interest in my candidacy. The questions could be categorized into three areas: basic algorithms/data structures, brainteasers, and web-specific questions.

Finally, I underwent three final interviews, each lasting approximately one hour. During one of these interviews, I was unexpectedly asked to write bubble sort on paper and then discuss its asymptotic complexity bounds and how to prove them. While I recognize these are relatively straightforward concepts, one can be caught off guard.

I thoroughly enjoyed the interview process; all interviewers were intelligent and polite. Ultimately, I received approval from each team that interviewed me and had to choose the team with which I wanted to work the most.

Everything proceeded well, but the offered salary was at the lower end of my desired range. I inquired with HR about raising the salary to at least the middle of my range, but this was not possible. Consequently, I accepted an offer from another company.

Write an O(n) time algorithm that finds if there exists a permutation of characters for a given string such that it becomes a palindrome. You may assume that the input string has no whitespace characters.