Microsoft Corporation Software Developer Interview Questions, Process, and Tips

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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Round duration - 45 minutes
Round difficulty - Easy

It was in the late afternoon. I was vey nervous, but the interviewer was very friendly. I managed to solve the questions early, so we discussed general things about the company and its culture.

Q1. 
Rooms and Keys Problem Statement
Given some information about rooms in a military camp, where rooms are numbered from 0 to 'N-1'. Each room may contain keys to some other rooms. You can only visit a room ...read more
Ans. 
Determine if all rooms can be visited starting from room 0 with given keys information.
• Use depth-first search (DFS) to traverse through rooms and keys.

• Keep track of visited rooms to avoid infinite loops.

• Check if all rooms have been visited at the end.
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Q2. 
Detect the First Node of the Loop in a Singly Linked List
You are provided with a singly linked list that may contain a cycle. Your task is to return the node where the cycle begins, if such a cycle exist...read more
Ans. 
To detect the first node of the loop in a singly linked list, we can use Floyd's Cycle Detection Algorithm.
• Use Floyd's Cycle Detection Algorithm to find the meeting point of the slow and fast pointers in the linked list.

• Reset one of the pointers to the head of the linked list and move both pointers at the same speed until they meet at the start of the cycle.

• The node where the pointers meet is the first node of the loop
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Round duration - 30 minutes
Round difficulty - Medium

The duration of the round was 30 minutes. It was conducted in the morning hours. The interviewer asked me many questions regarding my internship experience and my project. Later we discussed some problem solving.

Round duration - 75 minutes
Round difficulty - Hard

This round was conducted early in the morning. The interviewer was highly experienced and very friendly. He discussed about his life journey and his experience with the company.
Overall the experience was good, getting interviewed by such experienced person

Q1. 
Time to Burn Tree Problem
You are given a binary tree consisting of 'N' unique nodes and a start node where the burning will commence. The task is to calculate the time in minutes required to completely b...read more
Ans. 
Calculate the time in minutes required to completely burn a binary tree starting from a given node.
• Traverse the tree to find the longest path from the start node to a leaf node.

• The time to burn the entire tree is equal to the length of the longest path.

• Simulate the burning process by incrementing the time for each level of the tree.
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Round duration - 1 hour
Round difficulty - Medium

Q1. 
First Missing Positive Problem Statement
You are provided with an integer array ARR of length 'N'. Your objective is to determine the first missing positive integer using linear time and constant space. T...read more
Ans. 
Find the smallest positive integer missing from an array of integers.
• Iterate through the array and mark positive integers as visited by changing the sign of the corresponding index.

• After marking all positive integers, iterate again to find the first positive integer with a positive value.

• Return the index of the first positive integer found plus one as the answer.
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Round duration - 75 minutes
Round difficulty - Easy

This was the coding round which consisted of three coding questions and the time limit was of 75 minutes. The platform used was Co-Cubes. 3 questions were asked of 2, 3 and 5 marks respectively with varying difficulty.

Q1. 
Nearest Multiple of 10 Problem Statement
Given an integer N, find the nearest multiple of 10. If there are multiple nearest multiples, return the smallest one.
Input:
The first line contains an integer ...read more
Ans. 
Given an integer, find the nearest multiple of 10. If multiple nearest multiples, return the smallest one.
• Iterate through each test case

• Calculate the remainder when dividing N by 10

• If remainder is less than or equal to 5, nearest multiple is N - remainder

• If remainder is greater than 5, nearest multiple is N + (10 - remainder)
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Q2. 
Day of the Week Calculation
Your task is to create a function that determines the day of the week for any given date, whether in the past or the future.
Input:
The first line consists of an integer 'T',...read more
Ans. 
Create a function to determine the day of the week for any given date.
• Parse the input integers to create a date object

• Use a library or algorithm to calculate the day of the week for the given date

• Return the corresponding day of the week as a string
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Q3. 
Delete N Nodes After M Nodes in a Linked List
Given a singly linked list and two integers 'N' and 'M', traverse the linked list to retain 'M' nodes and then delete the next 'N' nodes. Continue this proces...read more
Ans. 
Traverse a linked list to retain 'M' nodes and then delete the next 'N' nodes, repeating until the end of the list.
• Create a function that takes the head of the linked list, 'N', and 'M' as input parameters.

• Traverse the linked list, retaining 'M' nodes and deleting the next 'N' nodes in each iteration.

• Continue this process until the end of the linked list is reached.

• Update the next pointers accordingly to skip 'N' nodes...read more
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Round duration - 30 minutes
Round difficulty - Easy

This was a written round and we were expected to write fully functional code, without any bugs and errors. Library functions used if any, had to be explained and if possible, code for that too (not that rigorous). Pseudocode and algorithms were also allowed. All the assumptions made had to be explained as well.

Q1. 
Look-And-Say Sequence Problem Statement
The Look-And-Say sequence is a series of positive integers generated in a specific pattern:
1, 11, 21, 1211, 111221, 312211, 13112221,...
To construct this sequen...read more
Ans. 
The Look-And-Say sequence is a series of positive integers generated in a specific pattern based on the count of digits in the previous number.
• Implement a function to generate the Nth term of the Look-And-Say sequence efficiently.

• Use a loop to iterate through the sequence generation process.

• Keep track of the count of consecutive digits in each number to generate the next number.

• Handle the constraints of the number of t...read more
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Q2. 
Rearrange Array to Form Largest Number
Given an array ARR consisting of non-negative integers, rearrange the numbers to form the largest possible number. The digits within each number cannot be changed.
...read more
Ans. 
Rearrange the array elements to form the largest possible number by concatenating them.
• Sort the array elements in a custom way to form the largest number.

• Convert integers to strings for comparison while sorting.

• Handle edge cases like leading zeros in the final number.

• Example: For input [12, 5, 34], the output should be '53412'.
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Round duration - 50 minutes
Round difficulty - Easy

The interviewer was very friendly and started asking me questions by making me comfortable.

Q1. 
Simplify Directory Path Problem Statement
You are provided with a directory path in Unix-style notation, and your task is to simplify it according to given rules.
In a Unix-style file system:
• A dot (...read more
Ans. 
The task is to simplify a directory path in Unix-style notation according to given rules.
• Use a stack to keep track of directories while iterating through the input path.

• Handle cases for '.', '..', and multiple slashes to simplify the path.

• Return the simplified path starting with a slash and without a trailing slash.
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Q2. 
Polynomial Simplification Problem Statement
You are provided with two arrays representing the coefficients and degrees of a polynomial expression. Your task is to simplify this polynomial into its general...read more
Ans. 
Simplify a polynomial expression by combining like terms and arranging them in descending order of degrees.
• Iterate through the coefficients and degrees arrays to combine like terms

• Create a map to store coefficients based on degrees

• Sort the map keys in descending order to get the simplified polynomial
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Round duration - 40 minutes
Round difficulty - Easy

This round was focused on resume and projects

Round duration - 30 minutes
Round difficulty - Easy

This round was basically a mix of HR and creative design round. The interviewer wanted to check whether the candidate can think out-of-the-box with regard to any given problem and come up with unique, optimized solutions.

Round duration - 90 minutes
Round difficulty - Easy

This round was the online coding test conducted on the platform Mettl. The languages allowed were C, C++, Java and Python. There were three questions. One was of graphs (Depth-first search), other was a big integer problem and the third was a string problem.

Q1. 
Graph Coloring Problem Statement
You are provided with a graph consisting of N vertices, numbered from 1 to N, and M edges. Your task is to color the graph using two colors, Blue and Red, such that no two...read more
Ans. 
Given a graph with vertices and edges, determine if it can be colored using two colors without adjacent vertices sharing the same color.
• Check if the graph is bipartite using graph coloring algorithm like BFS or DFS.

• If the graph is bipartite, return 'Possible' with a valid coloring assignment.

• If the graph is not bipartite, return 'Impossible'.
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Q2. 
String Compression Problem Statement
Write a program to perform basic string compression. For each character that repeats consecutively more than once, replace the consecutive duplicate occurrences with t...read more
Ans. 
Write a program to compress a string by replacing consecutive duplicate characters with the character followed by the number of repetitions.
• Iterate through the string and count consecutive occurrences of each character

• Append the character and its count to a new string

• Return the compressed string if it is shorter than the original, else return the original string

• Handle edge cases like single characters or when compresse
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Round duration - 60 minutes
Round difficulty - Easy

This was a pen and paper subjective interview round. You were expected to write full code on paper. Make sure you use proper names for the variables and write comments explaining very clearly what the code does. Also, try writing code in good handwriting which can be understood by the interviewer.

Q1. Find the total number of palindromic substrings in a given string.
Ans. 
Count total palindromic substrings in a given string.
• Iterate through each character in the string and consider it as the center of a palindrome. Expand outwards to find all palindromic substrings.

• Use dynamic programming to efficiently check if a substring is a palindrome.

• Consider both odd-length and even-length palindromes.

• Example: Input 'ababa', output 7 (a, b, a, b, a, aba, aba)
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Round duration - 45 minutes
Round difficulty - Easy

The interview took place in the morning and the interviewer was very friendly.

Q1. 
Count Inversions Problem Statement
Let A[0 ... n-1] be an array of n distinct positive integers. An inversion of A is a pair of indices (i, j) such that i < j and A[i] > A[j]. Given an integer array...read more
Ans. 
Count the number of inversions in an array of distinct positive integers.
• Use merge sort algorithm to count inversions efficiently.

• Divide the array into two halves and recursively count inversions in each half.

• Merge the two sorted halves while counting split inversions.

• Time complexity can be optimized to O(n log n) using merge sort.

• Example: For input A = [2, 4, 1, 3, 5], the output should be 3.
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Q2. 
Sum Tree Conversion Problem Statement
Transform a given binary tree into a sum tree where each node is replaced by the sum of its immediate children's values. Leaf nodes should be replaced with 0. Then, p...read more
Ans. 
Convert a binary tree into a sum tree by replacing each node with the sum of its children's values, and return the preorder traversal.
• Traverse the tree recursively and replace each node with the sum of its children's values

• Leaf nodes should be replaced with 0

• Perform a preorder traversal on the transformed sum tree to get the final result
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Round duration - 30 minutes
Round difficulty - Easy

The HR Interview round was held in the morning and it was right after my technical interview.