Microsoft Corporation Software Developer Interview Questions, Process, and Tips

Round duration - 90 minutes
Round difficulty - Hard

Q1. 
Stock Buying and Selling Problem Statement
Given an array of stock prices where each element represents the stock price for a given day, determine the maximum profit you can achieve from buying and sellin...read more
Ans. 
Determine maximum profit from buying and selling stocks on different days.
• Iterate through the array of stock prices and calculate the profit for each pair of days.

• Keep track of the maximum profit obtained by selling and buying stocks on different days.

• Return the maximum profit achieved.
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Round duration - 40 Minutes
Round difficulty - Medium

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.
• Perform a depth-first search (DFS) to calculate the time taken to burn the entire tree.

• Track the time taken for each node to catch fire and burn the tree accordingly.

• Consider the adjacency of nodes to determine the spread of fire.

• Handle cases where the start node is at different levels in the tree.

• Optimize the solution to
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Round duration - 40 minutes
Round difficulty - Easy

Q1. 
Flatten Binary Tree Problem Statement
Given a binary tree consisting of integer values, your task is to convert the binary tree into a linked list where the nodes of the linked list follow the same order ...read more
Ans. 
Convert a binary tree into a linked list following pre-order traversal order.
• Perform pre-order traversal of the binary tree and convert it into a linked list.

• Use the right pointer of the binary tree as the 'next' pointer for the linked list.

• Set the left pointer to NULL for each node in the linked list.

• Example: Input - 1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1, Output - 1 2 4 7 3 5 6
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Round duration - 25 Minutes
Round difficulty - Hard

Q1. Can you provide a code example that demonstrates communication between two processes?
Ans. 
Demonstrate communication between two processes using inter-process communication (IPC) methods.
• Use sockets for communication between two processes running on the same or different machines.

• Implement message passing using shared memory or message queues.

• Utilize pipes for communication between parent and child processes.
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Q2. 
Gray Code Problem Statement
You are given a number grayNumber. Your task is to find and return the Gray code sequence.
Explanation
The Gray code sequence should satisfy the following conditions:
1. Inc...read more
Ans. 
Find and return the Gray code sequence for a given number.
• Generate Gray code sequence by following the conditions provided in the problem statement.

• Ensure that consecutive numbers in the sequence differ by exactly 1 bit.

• Start the sequence with 0 and include numbers up to 2^grayNumber - 1.

• Return the sequence in decimal form as a list/vector.

• If multiple valid sequences exist, return any of them.
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Coding test had 3 questions

Q1. Started from dsa questions and went to Sql, Operating System and asked about my fav subject
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Round duration - 90 minutes
Round difficulty - Medium

it was around 9 :30 am interviewer was friendly

Q1. 
Find All Triplets with Zero Sum
Given an array Arr consisting of N integers, find all distinct triplets in the array that sum up to zero.
Explanation:
An array is said to have a triplet {Arr[i], Arr[j],...read more
Ans. 
Find all distinct triplets in an array that sum up to zero.
• Use a nested loop to iterate through all possible combinations of triplets.

• Sort the array to easily identify duplicates and skip unnecessary calculations.

• Use two-pointer technique to find the remaining element for each pair of elements.
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Round duration - 60 Minutes
Round difficulty - Medium

morning 11 am 
interviewer was friendly

Q1. 
Generate Binary Strings from Pattern
Given a string STR containing '0', '1', and '?' special characters, generate all possible strings by replacing each '?' with either '0' or '1'.
Input:
The first line...read more
Ans. 
Generate all possible binary strings by replacing '?' with '0' or '1'.
• Iterate through the input string and replace '?' with '0' and '1' recursively to generate all possible strings.

• Use backtracking to explore all possible combinations.

• Sort the generated strings lexicographically before returning the final result.
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Q2. 
Sum Root to Leaf Numbers
You are given an arbitrary binary tree consisting of N nodes, each associated with an integer value from 1 to 9. Each root-to-leaf path can be considered a number formed by concat...read more
Ans. 
Calculate the total sum of all root to leaf paths in an arbitrary binary tree.
• Traverse the tree in a depth-first manner to calculate the sum of each root to leaf path.

• Keep track of the current path sum and update it as you traverse the tree.

• Return the total sum modulo (10^9 + 7) as the final result.
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Round duration - 45 Minutes
Round difficulty - Hard

it was around 3
good recieving of interviewer

Q1. 
The Celebrity Problem
Imagine there are 'N' people at a party, each assigned a unique ID from 0 to N-1. A celebrity at the party is a person who is known by everyone but knows no one else.
Problem Statem...read more
Ans. 
Identify the celebrity at a party where one person knows everyone but is not known by anyone.
• Use a two-pointer approach to eliminate non-celebrity candidates.

• Start with two pointers at the beginning and end of the party.

• If A knows B, A cannot be the celebrity; move A to the right.

• If A does not know B, B cannot be the celebrity; move B to the left.

• Repeat until only one person remains, check if this person is known by ev...read more
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Round duration - 50 Minutes
Round difficulty - Easy

it was arround 2 afternoon

Round duration - 60 Minutes
Round difficulty - Medium

2 coding questions were asked

Q1. 
Count Squares in a Matrix
Given a matrix of size N * M, your task is to count the number of squares present within it.
Since the count can be extremely large, the result should be computed modulo 10⁹ + 7...read more
Ans. 
Count the number of squares in a given matrix modulo 10^9 + 7.
• Iterate through all possible square sizes from 1 to min(N, M)

• For each square size, count the number of squares that can fit in the matrix

• Return the total count modulo 10^9 + 7
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Q2. 
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 - 100 Minutes
Round difficulty - Medium

There was 1 coding question, and questions on CN, DBMS, OS and system design and also my resume.

Q1. 
Remove K Digits Problem Statement
You are given a non-negative integer represented as a string num and an integer k. Your task is to determine the smallest possible integer by removing exactly k digits fr...read more
Ans. 
Given a non-negative integer as a string and an integer k, find the smallest possible integer after removing k digits.
• Use a stack to keep track of the digits in non-decreasing order from left to right.

• Pop elements from the stack if the current digit is smaller than the top of the stack and k is greater than 0.

• Handle edge cases like leading zeros and ensuring the final result is not an empty string.

• Example: For num = "1...read more
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Round duration - 40 Minutes
Round difficulty - Medium

Interviewer was quite experienced he asked me 1 coding question and asked questions about college and resume

Q1. 
Longest Duplicate Substring Problem Statement
You are provided with a string 'S'. The task is to determine the length of the longest duplicate substring within this string. Note that duplicate substrings ...read more
Ans. 
Find the length of the longest duplicate substring in a given string.
• Use binary search to find the length of the longest duplicate substring.

• Implement Rabin-Karp algorithm for efficient substring search.

• Consider using a rolling hash function for substring comparisons.
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Round duration - 100 minutes
Round difficulty - Easy

3 coding Questions:
1st : Easy question based on simple loop iteration
2nd : Medium level Data structure question 
3rd : Medium level tree question(where we were not just required to complete the tree function but to build whole best from 
scratch) 

It was conducted from 1:30 - 3:00 pm.
The coding platform was very good (as auto indentation and auto completion of brackets were there) having camera on.

Q1. 
Ninja and the Storyteller Problem
Ninja is eager to listen to stories from the renowned Storyteller of Ninjaland. The storyteller charges 'Y' coins per story. However, for every set of 'X' stories told, N...read more
Ans. 
Calculate the total number of stories a ninja can hear from a storyteller based on given conditions and constraints.
• Calculate the number of stories Ninja can buy with available coins and without free stories.

• Calculate the number of free stories Ninja can get based on the number of stories bought.

• Add the total number of bought and free stories to get the final result.
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Q2. 
Buy and Sell Stock Problem Statement
You are tasked to help a friend with stock trading for the next 'N' days. He can either buy or sell a stock, with the condition that he can complete at most 2 transact...read more
Ans. 
Determine maximum profit from at most 2 stock transactions over 'N' days.
• Iterate through the prices array to find the maximum profit from 2 transactions.

• Keep track of the maximum profit by buying and selling stocks at the right times.

• Consider edge cases like when there are no profitable transactions.
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Round duration - 90 minutes
Round difficulty - Easy

This was a completely technical coding round where I was asked to solve the problems of data structures.

Q1. 
Minimum Cost Path Problem Statement
Given an integer matrix with dimensions m x n, determine the minimum cost required to reach from the cell (0, 0) to the cell (m-1, n-1).
You are allowed to move from a...read more
Ans. 
The problem involves finding the minimum cost path in a matrix by moving right, down, or diagonally down-right.
• Use dynamic programming to keep track of the minimum cost at each cell

• Consider the three possible directions for movement and calculate the cost accordingly

• Start from the top-left cell and iterate through the matrix to find the minimum cost path
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Q2. 
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 start node and calculate the time for fire to spread to all nodes

• Use a queue to keep track of nodes to be burned next

• Increment time for each level of nodes burned until the entire tree is burnt
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Round duration - 20 minutes
Round difficulty - Easy

It was held on Google meet platform
The interviewer was very experienced person and was very nice too.
He made me comfortable by first introducing himself in a very detailed way and then asking me mine introduction
Since I feel that his internet connection was not very good so he turned off his camera but I decided not to turn off mine as in online interviews your face reviles your confidence 
the interviewer mostly asked me questions about my interests in technical field and the project that I have done

Round duration - 60 Minutes
Round difficulty - Medium

It was a hiring drive for women. Interviewer was experienced person.

Q1. 
Construct Binary Tree from Inorder and Preorder Traversal
Given the preorder and inorder traversal sequences of a binary tree, your task is to construct the binary tree using these traversals.
Input:
Th...read more
Ans. 
Yes, it is possible to achieve a solution with O(N) time complexity using a hashmap to store the indices of elements in the inorder traversal.
• Use a hashmap to store the indices of elements in the inorder traversal for quick lookup.

• Recursively build the binary tree by selecting the root node from the preorder traversal and finding its index in the inorder traversal.

• Divide the inorder traversal into left and right subtre...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Cash Flow Minimization Problem
You are presented with a list of financial transactions among ‘n’ friends, where each transaction specifies who pays whom and how much. The objective is to minimize the cash...read more
Ans. 
The problem involves minimizing cash flow among friends by reorganizing debts through direct transfers or reducing total transactions.
• Given a list of financial transactions among 'n' friends, where each transaction specifies who pays whom and how much.

• Objective is to minimize the cash flow among the friends by reorganizing debts through direct transfers or reducing total transactions.

• Output a 2-D matrix showing the opt...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Total Strings Problem Description
Given a positive integer N, your task is to determine the number of strings of length N that can be created using only the characters 'a', 'b', and 'c'. The strings must a...read more
Ans. 
The problem involves determining the number of strings of length N that can be created using only the characters 'a', 'b', and 'c', with constraints on the number of 'b' and 'c' allowed.
• Use dynamic programming to count the number of valid strings for each length N.

• Consider the constraints on the number of 'b' and 'c' allowed in each string.

• Implement a function to calculate the result modulo 1000000007.

• For N = 2, valid ...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Ninja and the Tree: Correcting a Mistaken Binary Search Tree
Ninja is exploring the data structure of trees and while learning about Binary Search Trees (BST), she created her own. However, she unknowingl...read more
Ans. 
Identify and reverse the swap in a Binary Search Tree to recover the original structure.
• Identify the two nodes that are swapped in the Binary Search Tree.

• Swap the two nodes to restore the Binary Search Tree integrity.

• Ensure that the left subtree of a node contains only nodes with data less than the node's data, and the right subtree contains only nodes with data greater than the node's data.
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Round duration - 60 Minutes
Round difficulty - Medium

Hiring manager round

Q1. 
Maximum Meetings Problem Statement
Given the schedule of N meetings with their start time Start[i] and end time End[i], you need to determine which meetings can be organized in a single meeting room such ...read more
Ans. 
Given N meetings with start and end times, find the maximum number of meetings that can be organized in a single room without overlap.
• Sort the meetings based on their end times.

• Iterate through the sorted meetings and select the first meeting that doesn't overlap with the previous one.

• Repeat the process until all meetings are considered.

• Return the selected meetings in the order they are organized.
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