Microsoft Senior Software Engineer Interview - Oct 27, 2025

Note: The following interview questions and experiences were submitted by a verified user who recently interviewed at Microsoft for the Senior Engineer role and successfully received an offer.

Landing an interview at Microsoft as a Senior Engineer is an exciting but challenging opportunity. In this blog, I’ll share this verified user-submitted Microsoft interview experience, including coding and system design questions, along with solutions, insights, and preparation tips to help aspiring candidates.

Interview Questions

Here’s a list of all the questions asked during the interview rounds, as submitted by the verified user:

Round 1: Coding + System Design

Problem:

• Given a list of packages with dependencies, determine the order to install them.
• Dependencies are given as [a, b], meaning package a requires b first.

Follow-up Discussion (System Design):

• How to reduce system latency.
• How to handle high throughput.
• Techniques to improve scalability and fault tolerance.

Round 2: Coding, Complex Problem

Problem: Implement Trie with Lexicographical Queries

• Implement two functions:
  1. addWord(string word) → adds a word to the dictionary
  2. getWords(string pattern) → returns the three lexicographically smallest words starting with the given pattern

Follow-up:

• Handle wildcard characters . in the pattern efficiently.

Additional Discussion:

• Explaining how the verified user solved a previous complex problem, including debugging and solution approach.

Round 3: High-Level Design (HLD)

Problem: Design a Key-Value Store (like DynamoDB)

• Requirements: distributed, fault-tolerant, scalable.
• Focus: architecture, replication, consistency, and trade-offs.

Round 4: Hiring Manager Round

Discussion Points:

• Review of resume and consideration for role downgrade.
• Strengths and weaknesses from multiple perspectives (self, peers, manager).
• Draw a detailed diagram of a past project including throughput, latency, and architecture.
• Technical questions:
  • Difference between thread and process
  • CAP theorem
  • Relevant network protocols

Solutions and Discussion

Here’s how the verified user approached each round and solved the problems.

Round 1: Course Schedule II

Solution Approach:

1. Graph Modeling: Treat each package as a node; [a, b] is a directed edge b → a.
2. Cycle Detection: If a cycle exists, installation is impossible.
3. Topological Sort: Use DFS or Kahn’s algorithm to determine a valid installation order.

Python Example (DFS):

from collections import defaultdict

def findOrder(numCourses, prerequisites):
    graph = defaultdict(list)
    for a, b in prerequisites:
        graph[b].append(a)
    
    visited = {}
    stack = []
    
    def dfs(node):
        if node in visited:
            return visited[node]
        visited[node] = False
        for neighbor in graph[node]:
            if not dfs(neighbor):
                return False
        visited[node] = True
        stack.append(node)
        return True
    
    for i in range(numCourses):
        if i not in visited:
            if not dfs(i):
                return []  # Cycle detected
    return stack[::-1]

System Design Discussion:

• Reduce latency: caching, CDN, async processing
• Handle high throughput: load balancing, partitioning, sharding
• Improve scalability/fault tolerance: microservices, replication, circuit breakers

Round 2: Implement Trie with Lexicographical Queries

Solution Approach:

1. Trie Implementation: Nodes store children and end-of-word flag.
2. Adding Words: Traverse Trie and create nodes as needed.
3. Searching with Pattern: DFS, handle wildcards, return 3 smallest lexicographical matches.

Python Example:

class TrieNode:
    def __init__(self):
        self.children = {}
        self.isEnd = False

class Trie:
    def __init__(self):
        self.root = TrieNode()

    def addWord(self, word):
        node = self.root
        for char in word:
            if char not in node.children:
                node.children[char] = TrieNode()
            node = node.children[char]
        node.isEnd = True

    def getWords(self, pattern):
        res = []
        def dfs(node, path, i):
            if len(res) >= 3:
                return
            if i == len(pattern):
                if node.isEnd:
                    res.append(path)
                return
            if pattern[i] == '.':
                for ch in sorted(node.children.keys()):
                    dfs(node.children[ch], path + ch, i + 1)
            else:
                if pattern[i] in node.children:
                    dfs(node.children[pattern[i]], path + pattern[i], i + 1)
        dfs(self.root, '', 0)
        return res

Discussion Points:

• Trie for efficient prefix queries
• DFS for pattern search with lexicographical sorting
• Wildcard handling for performance

Round 3: High-Level Design, Key-Value Store

Design Approach:

1. Sharding/Partitioning: Distribute data across nodes using consistent hashing.
2. Replication: Multiple copies for fault tolerance.
3. Consistency: Quorum-based reads/writes; discuss CAP trade-offs.
4. Failure Handling: Replica failover, recovery processes.
5. Scalability: Horizontal scaling and load balancing.

Discussion Takeaways:

• Microsoft HLD rounds test reasoning, trade-offs, and communication, not just technical skills.

Round 4: Hiring Manager Round

Key Discussion Points:

• Resume review and willingness for downgrade.
• Strengths and weaknesses analysis from multiple perspectives.
• Project diagram with metrics: throughput, latency, architecture.
• Technical questions: threads vs processes, CAP theorem, network protocols.

Insights:

• Hiring managers evaluate fit, clarity, and problem-solving, not just coding.
• Be ready to discuss projects with concrete metrics.
• The verified user received an offer after this round, demonstrating that preparation and clear communication pay off.

Key Learnings from Microsoft Senior Engineer Interviews

• Coding & Algorithms: Focus on graphs, DFS/BFS, trie, topological sort.
• Problem-Solving: Explain your approach, discuss alternatives, justify trade-offs.
• System Design: Understand scalability, fault tolerance, distributed systems.
• Soft Skills: Clear communication and project explanation are critical.
• Preparation Tips:
  • Practice LeetCode medium/hard problems
  • Study distributed systems concepts
  • Prepare detailed project diagrams with metrics

This verified user’s experience highlights the importance of both technical and communication skills in Microsoft interviews. From coding rounds to system design and hiring manager discussions, understanding problem-solving, system architecture, and project impact is key. With the right preparation, you too can succeed and secure an offer at Microsoft.