Microsoft OA High-Frequency Questions 2026

Recently completed the Microsoft 2026 SDE Online Assessment (New Grad + Intern). One-line summary: Stable structure, but increasing difficulty and time pressure.

Platforms are mainly HackerRank or Codility, with a typical format:

• 2 questions
• 75–90 minutes (Codility sometimes 110 minutes)

Questions are mostly Medium, occasionally Medium-Hard, with stronger emphasis on:

• Engineering thinking
• Edge case handling
• Code robustness

1. Stacks / Blocks Conversion

Description:

Given an array where each number represents a stack of blocks. Every 2 blocks can merge into 1 and carry to the next stack. Repeat until no more merges are possible. Return remaining single blocks.

Example: [5,3,1]

Key Idea:

• Simulate from left to right
• Carry-over like binary addition (base-2 behavior)
• Use long for large values (up to 1e9)

Pitfalls:

• All 1s or all 0s
• Overflow issues
• Empty input

2. Circular Character Roll

Description:

Given a string s and an array roll, for each roll[i], increment the first roll[i] characters cyclically. ('z' → 'a')

Optimized Approach:

• Avoid brute force
• Use difference array + prefix sum
• Apply total shifts once (mod 26)

Why Important:

Classic 2026 high-frequency pattern testing string optimization.

3. Subarray Permutation Check

Description:

Given a permutation of 1..N, check if there exists a subarray of length K that forms a valid permutation.

Key Idea:

• Sliding window
• Track max + uniqueness
• Condition: max == K and no duplicates

Optimization: O(N) required — brute force will TLE.

4. String Without 3 Consecutive Letters

Description:

Given a string of 'a' and 'b', remove minimum characters to avoid 'aaa' or 'bbb'.

Approach:

• Greedy traversal
• Track consecutive count
• Delete when count exceeds 2

Variants:

• Lexicographically smallest string problems

5. Other High-Frequency Topics (2026)

• Graph: Connected components (Union-Find / DFS)
• DP: Stock trading, House Robber, Jump Game VI
• Sliding Window: Subarray optimization
• Greedy: Load balancing / task allocation
• BFS: Shortest path / escape problems

Microsoft OA 2026 Strategy

Platform:

• HackerRank (most common)
• Codility (stricter performance constraints)

Difficulty Trend:

• Medium-focused
• More edge cases + optimization

Preparation Tips:

• Practice Microsoft-tagged LeetCode problems
• Focus on Arrays, Strings, DP, Graph
• Simulate real test (2 questions timed)
• Reserve 10 minutes for edge case validation

Common Mistakes:

• Misreading problem statements
• Ignoring edge cases
• Using O(N²) solutions

Final Thoughts

Microsoft OA is a critical screening stage before Virtual Onsite (Coding + System Design + Behavioral).

If you're preparing for Microsoft SDE / Intern 2026:

• Need full solutions (Python / Java)?
• Want full high-frequency question sets?
• Curious about interview rounds (Team Match, Behavioral)?

Feel free to reach out.

Good luck with your Microsoft OA — stay consistent and keep pushing 🚀