Recently took an Akuna OA with three coding problems. Overall, the difficulty was manageable, focusing mainly on simulation, basic DP, and rule-based string processing.
There were no particularly tricky data structures, but the problems required careful reading and attention to edge cases. Here’s a quick breakdown of the three questions and the key ideas behind each one.
Problem 1: Server Error Replacement
Given server logs containing success or error, a server is replaced whenever it records 3 consecutive errors. After a replacement, the error counter resets. A success also resets the consecutive error count.
Approach: Use a HashMap to track the current consecutive error count for each server. Scan the logs once, incrementing the count on error and resetting it on success. When the count reaches 3, increment the replacement counter and reset the count.
Complexity: O(m) time and O(n) space.
The two details to watch are simple but easy to miss: success must reset the counter, and replacement must reset it as well.
Problem 2: Maximum Remaining Drone Battery
A drone starts with 100 units of battery and can begin from any position in the first row of an n × m grid. From each cell, it can move to the next row at column j-1, j, or j+1. Each cell consumes a certain amount of battery. The goal is to maximize the remaining battery after reaching the last row.
Approach: This is a standard grid DP problem.
Initialize the first row with:
dp[j] = 100 - city[0][j]For every following row, take the maximum remaining battery from the valid three positions in the previous row, then subtract the current cell's cost.
Complexity: O(nm) time. A rolling array reduces the space complexity to O(m).
Problem 3: Vowel Substring Game
Alex and Chris take turns removing substrings based on the number of vowels they contain. The task is to determine the winner for each input string.
For this particular version, the practical conclusion was essentially:
String contains a vowel → Alex
No vowels → Chris
The implementation is therefore straightforward: scan each string and check whether it contains one of a, e, i, o, or u.
For different versions of this problem, make sure to follow the exact statement and examples, especially the rules involving vowel parity and the winner when there are no valid moves.
What This Akuna OA Actually Tests
This set does not rely heavily on advanced algorithms. Instead, it tests whether you can read the rules carefully, maintain state correctly, handle boundaries, and implement basic DP without mistakes.
Before submitting, I would specifically check:
- Whether consecutive states are reset correctly
- Whether DP initialization is correct
- Whether grid boundaries are handled safely
- Whether special cases match the problem statement
- Whether the output format exactly matches the required format
Preparing for Akuna and Other Trading-Firm OAs?
If you're preparing for Akuna, Optiver, Stripe, Amazon, or other SDE/Quant interviews, InterviewShow collects recent interview experiences, OA questions, and commonly tested topics to help you understand the actual question styles and interview processes before you start preparing.
Knowing the patterns in advance can make your preparation much more targeted and help you avoid spending time on the wrong types of problems.
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