Microsoft Corporation Interview Questions, Process, and Tips for Freshers

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Q1. Why you want to join our company
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Q2. Why you not want to join that comapny
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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 - 75 minutes
Round difficulty - Hard

This round was scheduled in the evening hours and all the participants were required to fill a form which was shared 2 days prior to the test date. This form was filled out probably for the security reasons and to ensure that no one disinterested participant gives the test.

Q1. 
Validate BST Problem Statement
Given a binary tree with N nodes, determine whether the tree is a Binary Search Tree (BST). If it is a BST, return true; otherwise, return false.
A binary search tree (BST)...read more
Ans. 
Validate if a given binary tree is a Binary Search Tree (BST) or not.
• Check if the left subtree of a node contains only nodes with data less than the node's data.

• Check if the right subtree of a node contains only nodes with data greater than the node's data.

• Ensure that both the left and right subtrees are also binary search trees.
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Q2. 
Longest Palindromic Subsequence Problem Statement
Given a string A consisting of lowercase English letters, determine the length of the longest palindromic subsequence within A.
Explanation:
• A subsequ...read more
Ans. 
Find the length of the longest palindromic subsequence in a given string.
• Use dynamic programming to solve this problem efficiently.

• Create a 2D array to store the lengths of palindromic subsequences for different substrings.

• Fill the array diagonally based on the characters in the string.

• Return the length of the longest palindromic subsequence for each test case.
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Round duration - 45 minutes
Round difficulty - Medium

There was only one female interviewer for this round. She continuously interacted with me and was giving me some good situational problems that were not very easy to answer. Basically those were open-minded questions which can be answered both ways and that's why I found it quiet hard as per my nature but at the end things went well for me.

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 - 60 Minutes
Round difficulty - Easy

There were 3 coding questions of various difficulty level

Q1. 
LRU Cache Design Question
Design a data structure for a Least Recently Used (LRU) cache that supports the following operations:
1. get(key) - Return the value of the key if it exists in the cache; otherw...read more
Ans. 
Design a Least Recently Used (LRU) cache data structure that supports get and put operations with capacity constraint.
• Implement a doubly linked list to maintain the order of keys based on their recent usage.

• Use a hashmap to store key-value pairs for quick access and update.

• When capacity is reached, evict the least recently used item before inserting a new item.

• Update the order of keys in the linked list whenever a key ...read more
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Q2. 
Minimum Operations Problem Statement
You are given an array 'ARR' of size 'N' consisting of positive integers. Your task is to determine the minimum number of operations required to make all elements in t...read more
Ans. 
Determine minimum operations to make all array elements equal using addition, subtraction, multiplication, or division.
• Iterate through array to find the maximum and minimum elements.

• Calculate the difference between maximum and minimum elements.

• The minimum number of operations needed is the difference between the maximum and minimum elements.
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Q3. 
N Queens Problem
Given an integer N, find all possible placements of N queens on an N x N chessboard such that no two queens threaten each other.
Explanation:
A queen can attack another queen if they ar...read more
Ans. 
The N Queens Problem involves finding all possible placements of N queens on an N x N chessboard without threatening each other.
• Use backtracking algorithm to explore all possible configurations

• Check if the current placement is safe by verifying rows, columns, and diagonals

• Print valid configurations where queens do not attack each other
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Round duration - 80 Minutes
Round difficulty - Easy

Asked various coding questions and their implementations

Q1. 
Number of Islands Problem Statement
You are provided with a 2-dimensional matrix having N rows and M columns, containing only 1s (land) and 0s (water). Your goal is to determine the number of islands in t...read more
Ans. 
Count the number of islands in a 2D matrix of 1s and 0s.
• Use Depth First Search (DFS) or Breadth First Search (BFS) to traverse the matrix and identify connected groups of 1s.

• Maintain a visited array to keep track of visited cells to avoid redundant traversal.

• Increment the island count each time a new island is encountered.
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Q2. 
Reverse Stack with Recursion
Reverse a given stack of integers using recursion. You must accomplish this without utilizing extra space beyond the internal stack space used by recursion. Additionally, you ...read more
Ans. 
Reverse a given stack of integers using recursion without using extra space or loops.
• Use recursion to pop all elements from the original stack and store them in function call stack.

• Once the stack is empty, push the elements back in reverse order using recursion.

• Make use of the top(), pop(), and push() stack methods provided.

• Example: If the input stack is [1, 2, 3], after reversal it should be [3, 2, 1].
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Q3. 
Pair Sum Problem Statement
You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to find and return a list of all pairs of elements where each sum of a pair equals 'S'.
Note:
...read more
Ans. 
Find pairs of elements in an array that sum up to a given value, sorted in a specific order.
• Iterate through the array and for each element, check if the complement (S - current element) exists in a set.

• If the complement exists, add the pair to the result list.

• Sort the result list based on the criteria mentioned in the problem statement.
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Round duration - 30 Minutes
Round difficulty - Easy

HR was very friendly

Round duration - 120 Minutes
Round difficulty - Easy

Total 3 coding questions were there, out of which I don't remember the last one.

Q1. 
Ninja's Dance Competition Pairing Problem
Ninja is organizing a dance competition and wants to pair participants using a unique method. Each participant chooses a number upon entry, and Ninja selects a nu...read more
Ans. 
Find the number of distinct pairs of participants with a given difference in their chosen numbers.
• Iterate through the list of numbers and check for pairs with the required difference 'K'.

• Use a hash set to keep track of unique pairs to avoid counting duplicates.

• Return the size of the hash set as the number of distinct pairs.
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Q2. 
Longest Common Prefix After Rotation
You are given two strings 'A' and 'B'. While string 'A' is constant, you may apply any number of left shift operations to string 'B'.
Explanation:
Your task is to calcu...read more
Ans. 
Calculate minimum left shift operations to achieve longest common prefix between two strings.
• Apply left shift operations to string B to find longest common prefix with string A

• Count number of shifts needed to achieve longest common prefix

• Handle circular rotation of characters in string B

• Return minimum number of left shift operations for each test case
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Round duration - 60 Minutes
Round difficulty - Easy

Q1. 
Rotate Matrix by 90 Degrees Problem Statement
Given a square matrix 'MATRIX' of non-negative integers, rotate the matrix by 90 degrees in an anti-clockwise direction using only constant extra space.
Inpu...read more
Ans. 
Rotate a square matrix by 90 degrees in an anti-clockwise direction using constant extra space.
• Iterate through each layer of the matrix from outer to inner layers

• Swap elements in groups of 4 to rotate the matrix

• Handle odd-sized matrices separately by adjusting the loop boundaries
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Q2. 
Problem: Sort an Array of 0s, 1s, and 2s
Given an array/list ARR consisting of integers where each element is either 0, 1, or 2, your task is to sort this array in increasing order.
Input:
The input sta...read more
Ans. 
Sort an array of 0s, 1s, and 2s in increasing order.
• Use a three-pointer approach to partition the array into sections for 0s, 1s, and 2s.

• Iterate through the array and swap elements based on their values and the pointers.

• After sorting, the array will have 0s at the beginning, followed by 1s, and then 2s.
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Round duration - 60 Minutes
Round difficulty - Easy

This was HR + Technical round
He started with questions on projects and Os and Dbms and Oops
Then asked one coding question

Q1. 
Number of Islands Problem Statement
You are given a non-empty grid that consists of only 0s and 1s. Your task is to determine the number of islands in this grid.
An island is defined as a group of 1s (re...read more
Ans. 
The task is to determine the number of islands in a grid of 0s and 1s connected horizontally, vertically, or diagonally.
• Iterate through the grid and perform depth-first search (DFS) to find connected 1s forming islands

• Mark visited cells to avoid counting the same island multiple times

• Count the number of islands found during DFS traversal
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