Microsoft interview questions

Microsoft SDE Interview Preparation Guide
VM-STUDYPOINT:

Complete Microsoft SDE Interview Preparation Guide—everything in one place.👇

🧠 1. Core Computer Science Concepts

✅ Operating Systems

  • Process vs Thread:

    • Process: Independent, separate memory space

    • Thread: Lightweight process, shares memory with other threads in same process

  • Deadlock: Circular wait for resources.

    • Prevent using: ordering of resource requests, timeout, deadlock detection

✅ DBMS

  • Normalization:

    • 1NF: No repeating groups

    • 2NF: No partial dependency

    • 3NF: No transitive dependency

  • Transactions (ACID):

    • Atomicity, Consistency, Isolation, Durability

  • Indexing: Faster lookups (B-Tree, Hash-based)

✅ Computer Networks

  • TCP vs UDP:

    • TCP: Reliable, ordered (e.g. HTTP)

    • UDP: Fast, no guarantee (e.g. video stream)

  • DNS: Converts domain name to IP

  • OSI Model: 7 layers – Physical to Application

✅ OOP Concepts

  • Encapsulation: Hide internal state

  • Abstraction: Expose only essentials

  • Inheritance: Reuse code

  • Polymorphism: One interface, many forms (method overriding, overloading)

📊 2. DSA (Data Structures & Algorithms)

🔹 Must-Practice Topics:

  • Arrays, Strings

  • HashMaps, Sets

  • Linked Lists

  • Trees (Binary Tree, BST)

  • Graphs (BFS/DFS)

  • Recursion, Backtracking

  • Sliding Window, Two Pointer

  • Dynamic Programming

🔹 Examples in Python & C++

Q1: Two Sum (HashMap)

Python:

python
def two_sum(nums, target):
            map = {}
            for i, num in enumerate(nums):
                if target - num in map:
                    return [map[target - num], i]
                map[num] = i

C++:

cpp
vector<int> twoSum(vector<int>& nums, int target) {
            unordered_map<int, int> map;
            for (int i = 0; i < nums.size(); ++i) {
                if (map.count(target - nums[i]))
                    return {map[target - nums[i]], i};
                map[nums[i]] = i;
            }
            return {};
        }

Q2: Detect Cycle in Linked List (Floyd’s)

Python:

python
def has_cycle(head):
            slow = fast = head
            while fast and fast.next:
                slow = slow.next
                fast = fast.next.next
                if slow == fast:
                    return True
            return False

Q3: Longest Substring Without Repeating Characters

Python (Sliding Window):

python
def lengthOfLongestSubstring(s):
            left, max_len = 0, 0
            seen = {}
            for right in range(len(s)):
                if s[right] in seen:
                    left = max(left, seen[s[right]] + 1)
                seen[s[right]] = right
                max_len = max(max_len, right - left + 1)
            return max_len

🏗️ 3. Basic System Design (For Freshers)

Q: Design a URL Shortener

  • Short Key = Base62(id)

  • Store original ↔ short mapping in DB

  • Cache top links with Redis

  • REST API to create and redirect

  • Optional: Analytics (count, geo info)

Tips:

  • Know basic components (DB, cache, load balancer)

  • Mention horizontal scaling

  • No need for code unless asked

💬 4. Behavioral Questions (STAR Format)

Q: Tell me about a time you faced a technical challenge.

S: Our app crashed during login.
T: I had to debug and fix under pressure.
A: Used logging, binary search approach in code to isolate the bug.
R: Found the issue in token parsing and fixed it — prevented 20+ future crashes.

Q: Why Microsoft?

  • I'm passionate about products like VS Code, GitHub, and Azure.

  • Microsoft values innovation, inclusion, and global impact — aligns with my goals.

  • I want to grow in a place where I’m constantly learning from brilliant minds.

🧪 5. Microsoft Interview Process (Fresher - SDE)

RoundDetails
OACodility/HackerRank: 2-3 DSA Qs (60-90 min)
Tech 1DSA + OOPs + CS core
Tech 2Projects, basic system design
HRSTAR, resume deep-dive, teamwork, why MS

🧠 6. Microsoft Online Assessment Tips

  • Use Python if you're comfortable — concise + fast to write

  • Practice on LeetCode, HackerRank, and InterviewBit

  • Use dry-run technique for debugging

  • Always communicate your thought process clearly

📆 7. 30-Day Study Plan

WeekFocus
1Arrays, Strings, Hashing, OS, DBMS
2LinkedList, Trees, Sorting, OOPs
3Recursion, Graphs, CN, System Design
4Mock interviews, STAR prep, project revision

🔗 Resources

Let's level up and dive into mock Microsoft interview questions section-wise, with full answers and explanations so you get the feel of the real thing. Let’s break this down into:

🔥 Section 1: Data Structures & Algorithms — Mock Interview Q&A

Q1. Merge Intervals

Given: A list of intervals [[1,3],[2,6],[8,10],[15,18]]
Output: [[1,6],[8,10],[15,18]]

🧠 Idea: Sort by start time, merge overlapping ones.

Python:

python
def merge(intervals):
                intervals.sort()
                merged = []
                for i in intervals:
                    if not merged or merged[-1][1] < i[0]:
                        merged.append(i)
                    else:
                        merged[-1][1] = max(merged[-1][1], i[1])
                return merged

👉 Microsoft Favorite for testing sorting logic + edge cases.

Q2. Find Median in a Data Stream

You’re given a stream of integers. Design a class to return the median at any time.

🧠 Use two heaps: max-heap (left half) & min-heap (right half)

Python (using heapq)

python
import heapq
            
            class MedianFinder:
                def __init__(self):
                    self.low = []  # max heap (invert values)
                    self.high = [] # min heap
            
                def addNum(self, num):
                    heapq.heappush(self.low, -num)
                    heapq.heappush(self.high, -heapq.heappop(self.low))
                    if len(self.low) < len(self.high):
                        heapq.heappush(self.low, -heapq.heappop(self.high))
            
                def findMedian(self):
                    return (-self.low[0] + self.high[0]) / 2 if len(self.low) == len(self.high) else -self.low[0]

🧠 Microsoft asked this in SDE intern round (2023).

💻 Section 2: OOPs and System Design (Fresher Level)

Q3. Design a Parking Lot (Object-Oriented Design)

Requirements:

  • Support for multiple levels

  • Each level has slots for cars, bikes

  • Methods: parkVehicle(), leaveSlot(), getFreeSlots()

🧱 Classes:

  • Vehicle (base)

  • Car, Bike (inherits Vehicle)

  • Slot, ParkingLot, Level

What they look for:

  • Clean inheritance

  • Association (Lot has Levels, Levels have Slots)

  • Not code—just class diagram + logic

Q4. Design an Online Code Editor (like LeetCode)

Ask: What components would you use?

✔️ Components:

  • Frontend: Code editor (Monaco/ACE)

  • Backend:

    • Auth & DB

    • Code runner (sandboxed docker container)

    • REST APIs to fetch questions, run code

  • Database: Store submissions, questions, users

👉 Talk about modularity, microservices, and security in sandboxing

🗣️ Section 3: HR + STAR Questions

Q5. Tell me about a time you worked in a team to complete a project.

S: Final year group project to build an expense tracking app
T: I was responsible for backend APIs
A: Used Flask + SQLite, created modular code, helped frontend with API integration
R: We submitted early and demo’d to great feedback—team got best project award

✅ Keep answers within 90–120 seconds using STAR

Q6. How do you handle failure?

"I believe failure is a part of the learning process. In one hackathon, our app crashed midway. Instead of giving up, we debugged overnight and presented a partial version that still showed our concept. We didn’t win, but the experience taught me quick decision-making and resilience."

📈 Want More?

Here’s what I can add next for you:

  1. More medium/hard DSA questions with step-by-step approach

  2. Mock behavioral Qs tailored to your resume

  3. Project-based questions: How to present your academic/final year projects smartly

  4. Microsoft internship/graduate round insights from past candidates

  5. Resume & LinkedIn optimization tips for Microsoft

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