Recently, many candidates have started receiving their 2026 Summer Intern online assessments. Here’s a recap of one JPMorgan Chase OA completed on the HackerRank platform, for those who are currently preparing.
The structure was straightforward: two coding questions. The time allocation was reasonable, and the overall difficulty leaned toward fundamental algorithm models rather than tricky edge-case implementation. If you’re comfortable with common patterns, this type of OA can be completed efficiently.
Question 1: Interval Flip Operations on an Array
The first problem provided an initial array and multiple interval operations. Each operation flipped the values within a given range. The goal was to return the final state of the array after all operations were applied.
A direct simulation approach would be inefficient for large inputs. Instead, the key insight is to track how many times each index is affected.
Optimized approach:
- Mark +1 at the start index of each interval
- Mark -1 right after the end index
- Run a prefix sum to compute how many times each position was modified
- If the count is odd, flip the value; if even, leave it unchanged
This is essentially a difference array + prefix sum optimization. The time complexity becomes O(n + m), which scales efficiently.
Question 2: Maximum Concurrent Tasks (Minimum Machines Required)
The second problem involved a list of tasks with start and end times. The question asked for the maximum number of tasks running simultaneously — equivalent to the minimum number of machines required.
This is a classic sweep line problem.
Solution outline:
- Mark +1 at each task’s start time
- Mark -1 at the moment after each task’s end time
- Sort all time events
- Scan chronologically while maintaining a running count
- The maximum value observed during the scan is the answer
The logic is clean and implementation is not complex, but careful boundary handling is important.
Overall Takeaways
This OA mainly tested familiarity with classic interval and timeline models:
- Difference array optimization
- Prefix sum accumulation
- Sweep line event processing
The difficulty was moderate, but speed and clarity of thinking made the difference. If you are preparing for 2026 Summer Intern roles, make sure these foundational models are second nature.
If you're currently preparing for online assessments and want to better understand common HackerRank / CodeSignal patterns or preparation strategies, feel free to reach out privately:
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