Microsoft Corporation Interview Questions, Process, and Tips

Round duration - 60 minutes
Round difficulty - Medium

This was the first round. The interviewer discussed two coding problems with me.

Q1. 
LCA of Binary Tree Problem Statement
You are given a binary tree of distinct integers, along with two nodes, ‘X’ and ‘Y’. Your task is to determine the Lowest Common Ancestor (LCA) of ‘X’ and ‘Y’.
The LC...read more
Ans. 
Find the Lowest Common Ancestor of two nodes in a binary tree.
• Traverse the binary tree to find the paths from the root to nodes X and Y.

• Compare the paths to find the last common node, which is the LCA.

• Handle cases where one node is an ancestor of the other.

• Consider using recursion to solve the problem efficiently.
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Q2. 
Median of Two Sorted Arrays
Given two sorted arrays A and B of sizes N and M, find the median of the merged array formed by combining arrays A and B. If the total number of elements, N + M, is even, the m...read more
Ans. 
Find the median of two sorted arrays by merging them and calculating the middle element(s).
• Merge the two sorted arrays into one sorted array.

• Calculate the median based on the total number of elements in the merged array.

• If the total number of elements is even, take the mean of the two middle elements as the median.
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Round duration - 45 minutes
Round difficulty - Easy

This was the second round. We started with a brief introduction. The interviewer then asked one coding problem and we had a long discussion on that problem only.

Q1. 
Possible Words From A Phone Number
After years of research, Ninja has invented a time machine and found himself in the era where T9 keypads were commonly used in mobile phones. Being curious, Ninja seeks ...read more
Ans. 
Given a string of digits from 2 to 9, determine all possible strings that can be generated using T9 keypad letter mappings.
• Create a mapping of digits to corresponding letters on a T9 keypad

• Use recursion to generate all possible combinations of letters for the input string

• Sort the generated strings lexicographically

• Return the array of generated strings
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Round duration - 40 minutes
Round difficulty - Easy

This was a typical managerial round. We started with a brief introduction. Then, the interviewer moved to my projects and started asking questions on one of the projects that he found interesting. At last, he asked me some questions based on Operating Systems.

Round duration - 90 minutes
Round difficulty - Easy

This round consists of 3 coding questions with a total time limit of 90 minutes. The first two questions were of easy level and the third question was of medium level. No two candidates had the same set of questions, the distribution of questions was random. The test was conducted on mettl platform with both audio and video on for monitoring on the candidate.

Q1. 
Running Median Problem
Given a stream of integers, calculate and print the median after each new integer is added to the stream.
Output only the integer part of the median.
Example:
Input:
N = 5  
Stre...read more
Ans. 
Calculate and print the median after each new integer is added to the stream.
• Use two heaps - a max heap to store the smaller half of the numbers and a min heap to store the larger half.

• Keep the sizes of the two heaps balanced to efficiently calculate the median.

• If the total number of elements is odd, the median will be the top element of the max heap.

• If the total number of elements is even, the median will be the avera
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Q2. 
Fruits and Baskets Problem Statement
You are given 'n' fruit trees planted along a road, numbered from 0 to n-1. Each tree bears a fruit type represented by an uppercase English alphabet. A Ninja walking ...read more
Ans. 
The Ninja must collect fruits from trees in consecutive order, maximizing the number of fruits in two baskets.
• Iterate through the trees while keeping track of the types of fruits collected in each basket.

• Use a sliding window approach to find the maximum number of fruits collected.

• Keep track of the count of each fruit type encountered to handle the condition of only two types of fruits in each basket.
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Q3. 
Dice Throws Problem Statement
You are given D dice, each having F faces numbered from 1 to F. The task is to determine the number of possible ways to roll all the dice such that the sum of the face-up num...read more
Ans. 
The task is to determine the number of possible ways to roll all the dice such that the sum of the face-up numbers equals the given 'target' sum.
• Use dynamic programming to solve the problem efficiently.

• Create a 2D array to store the number of ways to achieve each sum with the given number of dice.

• Iterate through the dice and faces to calculate the number of ways to reach each sum.

• Return the result modulo 10^9 + 7.

• Optim...read more
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Round duration - 50 miutes
Round difficulty - Medium

This was my first interview and I was a bit nervous. The interview was conducted on Microsoft Team. He told me to share my screen and write the pseudo code on notepad. The interviewer was very friendly and also gave me hints for the question. However, he mostly focused on optimization of the code. At the end of the question, few questions related to Operating Systems were asked.

Q1. 
Group Anagrams Problem Statement
Given an array or list of strings called inputStr, your task is to return the strings grouped as anagrams. Each group should contain strings that are anagrams of one anoth...read more
Ans. 
Group anagrams in an array of strings based on character frequency.
• Iterate through each string in the input array

• For each string, sort the characters and use the sorted string as a key in a hashmap to group anagrams

• Return the grouped anagrams as arrays of strings
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Round duration - 45 minutes
Round difficulty - Medium

The second round consisted questions related to concepts of object oriented programming and databases. At the end of the interview he asked me to explain any one good project. The interview lasted for 45 minutes. The interviewer was friendly and good.

Q1. 
Merge Sort Problem Statement
You are given a sequence of numbers, ARR. Your task is to return a sorted sequence of ARR in non-descending order using the Merge Sort algorithm.
Explanation:
The Merge Sort...read more
Ans. 
Implement Merge Sort algorithm to sort a given sequence of numbers in non-descending order.
• Divide the input array into two halves recursively until each array has only one element.

• Merge the sorted halves to produce a completely sorted array.

• Time complexity of Merge Sort is O(n log n).
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Round duration - 30 minutes
Round difficulty - Easy

This was my last round and I was a bit tensed. It was an HR round. The interviewer was very professional. He discussed and asked questions about my various achievements, my interests apart from the technical field and also asked about my projects. I made sure to answer all the questions confidently and calmly.

Round duration - 90 minutes
Round difficulty - Medium

The online coding round took place at 9:30 am in the morning. The platform was new so I got familiar with it in advance, a night before, to avoid any hassle during the test. There was camera proctoring and laptop screen sharing throughout the test. Multiple programming languages like Java, C, C++ and Python were allowed. There were 3 coding questions based on DSA. Questions were different for different candidates.

Q1. 
Distinct Strings With Odd and Even Swapping Allowed Problem Statement
You are provided with an array of strings, and your objective is to determine the number of unique strings within it.
A string is deeme...read more
Ans. 
Given an array of strings, determine the number of unique strings that cannot be transformed into another string by swapping characters at odd or even indices.
• Iterate through each string in the array and check if it can be transformed into another string by swapping characters at odd or even indices.

• Keep track of unique strings that cannot be transformed and return the count.

• Example: For array = ["abcd", "cbad", "bdac"...read more
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Q2. 
Rotational Equivalence of Strings Problem Statement
Given two strings 'P' and 'Q' of equal length, determine if string 'P' can be transformed into string 'Q' by cyclically rotating it to the right any num...read more
Ans. 
Check if one string can be transformed into another by cyclically rotating it to the right.
• Iterate through all possible rotations of string P and check if any of them match string Q.

• Use string concatenation to simulate cyclic rotations efficiently.

• Compare the rotated strings with string Q to determine if they are equivalent.
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Q3. 
Buses Origin Problem Statement
You have been provided with an array where each element specifies the number of buses that can be boarded at each respective bus stop. Buses will only stop at locations that...read more
Ans. 
Given an array representing number of buses at each bus stop, determine how many buses originate from each stop.
• Iterate through the array and for each element, increment the count of buses originating from the corresponding bus stop.

• Use an array to store the count of buses originating from each stop.

• Remember to consider the constraint of 1-based indexing for bus stops.
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Round duration - 45 Minutes
Round difficulty - Medium

The interview took place through Microsoft Teams at 2:00 pm. The platform was smooth and the interviewer was very friendly and told me that he isn't looking for bookish language answers but he only wants to check my understanding of CS subjects.

Q1. 
Longest Mountain Subarray Problem Statement
Given an array of integers representing the heights of mountains, determine the length of the longest subarray that forms a mountain shape.
A mountain subarray...read more
Ans. 
Find the length of the longest mountain subarray in an array of integers.
• Iterate through the array to find peaks.

• Expand from peaks to find ascending and descending slopes.

• Track the length of the mountain subarray and return the maximum length.
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Round duration - 55 Minutes
Round difficulty - Medium

The interview was conducted on Microsoft Teams and the interviewer was very friendly. He made sure I was comfortable and described his role at Microsoft.

Q1. 
Kth Largest Element Problem
Given an array containing N distinct positive integers and a number K, determine the Kth largest element in the array.
Example:
Input:
N = 6, K = 3, array = [2, 1, 5, 6, 3, ...read more
Ans. 
Find the Kth largest element in an array of distinct positive integers.
• Sort the array in non-increasing order and return the Kth element.

• Use a sorting algorithm like quicksort or heapsort for efficiency.

• Ensure the array contains distinct positive integers for accurate results.
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Q2. Can you describe the ACID properties in DBMS?
Ans. 
ACID properties in DBMS ensure data integrity and consistency.
• Atomicity: All transactions are either fully completed or fully aborted. For example, transferring money from one account to another should be completed in its entirety.

• Consistency: The database remains in a consistent state before and after the transaction. For example, if a constraint is violated during a transaction, the transaction will be rolled back.

• Is...read more
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Round duration - 60 Minutes
Round difficulty - Hard

The interview was conducted on Microsoft Teams and code was written on Notepad (screen shared). The interviewer was friendly and gave hints to reach the final solution.

Q1. 
Data Structure with Insert, Delete, and GetRandom Operations
Design a data structure that supports four operations: insert an element, remove an element, search for an element, and get a random element. E...read more
Ans. 
Design a data structure supporting insert, delete, search, and getRandom operations in constant time.
• Use a combination of hashmap and array to achieve O(1) time complexity for all operations.

• For insert operation, check if element exists in hashmap, if not add to array and hashmap.

• For remove operation, check if element exists in hashmap, if yes, remove from array and hashmap.

• For search operation, check if element exists...read more
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Q2. 
Convert BST to Sorted Doubly Linked List
You are given a Binary Search Tree (BST), and your task is to convert it into a sorted Doubly Linked List (DLL).
Example:
Consider the provided BST. The goal is ...read more
Ans. 
Convert a Binary Search Tree to a sorted Doubly Linked List efficiently.
• Implement a function to convert a BST to a sorted DLL.

• Use in-order traversal to efficiently convert the BST to DLL.

• Maintain pointers for the head and tail of the DLL.

• Ensure the left child of a node becomes the previous node and the right child becomes the next node in the DLL.
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Q3. What would your dream project be like?
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