I recently completed the Online Assessment (OA) for IBM, and the overall experience was quite smooth. Compared to other big tech companies, IBM’s coding questions tend to be more foundational. As long as you maintain consistent practice on LeetCode and are familiar with common algorithm templates, passing the OA is usually very achievable.
At the same time, I’ve been preparing for OA and VO rounds from companies like Amazon, Google, and Microsoft. Based on this experience, I’ve compiled and summarized several high-frequency IBM OA questions to help those who are currently preparing.
1. IBM OA Overview
- Typically 2 coding questions
- Relatively flexible time constraints
- Focus on fundamental algorithms and data structures
- Requires clean code and solid edge case handling
2. High-Frequency Questions
Question 1: High Load Timestamp Index
Description: Given an array load[] representing server load, return all indices i (0-based) where load[i] > 2 × average load. Return the indices in ascending order. If none exist, return an empty array.
Constraints: 1 ≤ n ≤ 2×10^5, 1 ≤ load[i] ≤ 10^9
Key Points: Array traversal, average calculation, precision handling
Question 2: Minimum Total Cost of Items
Description: There are numItems items, each with multiple pricing options given by itemId[] and cost[]. Choose one price per item such that the total cost is minimized. If any item has no available price, return -1.
Example: Minimum costs for items 0, 1, 2 are 7, 6, and 8 respectively, total cost = 21.
Key Points: Grouping + minimum value selection using hashmap or array
Question 3: Maximum Non-Overlapping Intervals
Description: Given n intervals [startTime[i], endTime[i]), find the maximum number of non-overlapping intervals.
Constraints: n ≤ 10^5
Key Points: Classic greedy algorithm (sort by end time and select greedily)
Question 4: Maximum Water Level Increase
Description: Given an array arr representing water levels, find the maximum difference arr[j] - arr[i] such that i < j and arr[i] < arr[j]. If no such pair exists, return -1.
Constraints: Up to 2×10^6 elements
Key Points: Single pass with tracking minimum value
3. Preparation Tips
- Master fundamental algorithm patterns: greedy, two pointers, prefix sum, hashmap
- Handle edge cases carefully (empty inputs, impossible cases returning -1, etc.)
- Practice input/output formats on platforms like HackerRank
- Write clean, readable code with clear variable naming
4. Professional Assistance
We have also compiled detailed solutions, optimized code templates, and common pitfalls for these IBM OA questions. If you need full solutions, feel free to reach out via message or comments.
If you are preparing for OA or VO interviews at top tech companies and want a more structured and reliable approach, we provide professional assistance services:
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Good luck with your interviews and wish you all the best in landing your dream offer!
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