I once faced one of the toughest interview processes of my career, which consisted of three rounds: an Online Assessment (OA), an online interview, and an onsite loop interview. Here’s how it unfolded.
The first round was an Online Assessment filled with two hard, one medium problems. I only had to manage to solve them in 75 minutes. The platform is Codepair which is kind of buggy in my opinion. The problem was a hard graph problem, I even solved this problem before but took the most time to write code the solution because the platform is very strange. I remember distinctly my previous failure attempt at the company because of this. The format of the problem is kinda strange too. The second is a medium problem where you are given N queens, you need to output the first queen index that attack another queen. I forgot the 3rd problem but it is also a hard problem.
I submitted my last problem in the last minute.
A few days later, I received an invitation for the second round: an online interview. This round consisted of a variant of a hard problem, and it was designed to test my problem-solving skills under pressure. The interview came in asked about by experience for 30 minutes, we shared a code pair link. He pasted the problem statement, I understood the requirement but couldn’t came up with a solution. I asked him for a hint. He said forget about the contraints. I immediately came up with a complete-search aka brute force.
The platform was buggy, we then managed to share screen and I coded on my VScode. Because I had only 30 minutes so I rushed to implement the solution I eventually arrived at a working solution. We were discussing about time complexity and he asked if I could optimize it further. I couldn’t improved on any except for small improvements on space complexity. I later learned that there is A* solution and some heuristics strategy to solve this problem. I left the interview feeling relieved that I had managed to solve the problem.
The final round was the onsite interview, which consisted of three loop interviews with different team members.
Interview 1: With a engineering leader He came in asked me about my working experience. Then ask me about a medium problem, I cleared it out easily, he told me to optimize space a bit. I think for a moment and propose a solution. He then game me a Trie problem. I gave him some non Trie solutions the ultimately came to the Trie solution. I told him I don’t very confident knowing all the details but he kept saying that it was totally ok. I propose a solution but when I get to write code on the white bug, I made bug everywhere. He eye-debuged my code in seconds. We are 5 minutes overdue. He wished me good luck and left the room.
Interview 2: Technical Problem This is when I completely flop. An engineer came in first asked me about my expierence. Then gave me about some kind of game strategy problem. I didn’t have a clue. He hinted me it was divide and conquer. I still don’t know how code it. I asked for another problem. He ask me to solve the “merge K sorted linked list”.
Interview 3: Technical Problem An engineer came in introducing about him self and asking about my prior expierence. Very chill and casual, then gave me a graph problem. I struggled for the whole time. He told me to solve an easy version of the problem. I couldn’t bring any solution. He hinted me and then I knew the solution for that small problem. I asked him the computer to write the code. He told me to write code in ideone.com, I managed to write the solution in just 5 minutes. He commented a bit about my code then leave. It takes me 2 weeks to finally understand the intended solution.
There was supposed to have an interview with the CTO but apparently he was busy so I didn’t get to meet him.
I knew that they will only asked hard level problems in the interview but I don’t think that they will be that hard. The lucky part is that I have a feeling that they will asked a Trie problem so I had brushed up on my Trie knowledge before hand. The unlucky part is that they game me strategy-based problem which I never liked. I didn’t get the offer in the end and I think it is fair. I gave it my best shot but I didn’t perform well enough.
The bar of hiring is amazing. I happened to know 2 of the interviewers are IOI medalist!