For 2026 New Grad candidates applying to IBM SDE roles, the Online Assessment has been rolling out frequently. The format is very straightforward: two pure coding questions on HackerRank, no behavioral sections, no mixed formats. The time limit is relatively generous, but passing in one attempt still depends heavily on correctly identifying the problem model and handling edge cases.
I cleared both questions with full AC on the first attempt. Below is a clean breakdown of the core logic, common pitfalls, and the exact thinking patterns you can directly reuse during practice or the real OA.
1. OA Overview & Common Pitfalls
Format-wise, the IBM OA is as clean as it gets: a single online coding session with two problems and no interruptions. Difficulty stays in the Easy to Medium range — no trick algorithms, no obscure data structures.
Where candidates usually lose points is not algorithm difficulty, but details: misreading grouping or ordering rules, missing boundary conditions, or overengineering the second question and running into performance issues.
A practical tip: spend the first 3–5 minutes reading the full problem statement carefully and walking through the sample cases. That small upfront investment saves much more time than debugging later.
2. Question 1: Log Status Validity Check (Grouped by Service ID)
Core Requirements
Each log entry contains a service ID (sid), a timestamp, and a status. The task is to validate logs grouped by service ID under the following rules:
- Logs must be grouped by sid.
- Within each group, logs must be sorted by timestamp in ascending order.
- The first status must be
DOWN. - Statuses must strictly alternate:
DOWN → UP → DOWN → UP ....
If any group violates the rules, that entire group is considered invalid. The final output is the total number of invalid groups.
Solution Approach
Use a hash map to group logs by service ID. For each group:
- Sort the logs by timestamp.
- Check whether the first status is
DOWN. - Iterate through the sequence and verify that adjacent statuses are different.
Increment the invalid group count as soon as a rule is broken.
Key Pitfalls
Skipping the timestamp sort is the most common mistake.
Another frequent miss is handling edge cases incorrectly:
a single log entry is valid only if its status is DOWN.
Also note that the task asks for the number of invalid groups, not invalid log entries.
3. Question 2: Shortest Subarray Containing k Increasing Elements
Problem Simplification
You are given a permutation (all elements are unique). The goal is to find the shortest contiguous subarray such that you can select k strictly increasing elements from it.
Because the array is a permutation, this simplifies to: the subarray must contain at least k distinct values.
Optimal Model: Sliding Window
Use a two-pointer sliding window approach:
- Expand the right pointer and include elements into the window.
- Track the number of distinct elements using a hash map or array.
- Once the count reaches at least
k, try shrinking the window from the left. - Update the minimum window length whenever the condition is satisfied.
This runs in O(n) time and avoids unnecessary complexity.
Why Not DP or Brute Force?
Many candidates overthink this problem and attempt recursive or DP-based solutions, which often lead to O(n²) complexity and timeouts. The challenge here is model selection, not algorithmic depth.
4. Practical Tips for 2026 IBM OA Preparation
IBM frequently tests classic patterns rather than exotic algorithms. Focus your prep on:
- Grouping + sorting by key
- Status transitions and sequence validation
- Sliding window with frequency counting
- Edge-case testing and clean input/output handling on HackerRank
Always test edge scenarios: empty input, single-element cases, invalid starting states, and windows that barely meet or exceed the threshold.
5. Final Thoughts
The 2026 IBM SDE OA is very manageable once you recognize the underlying templates: group-and-validate for Question 1, and sliding window optimization for Question 2. There is no hard algorithm barrier — precision and calm execution matter far more than speed.
If you're also preparing for OAs from companies like IBM, Amazon, or Microsoft and want extra support during real OA sessions, you can check out interview assistance options here: ProgramHelp Interview Assistance.
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