Microsoft Corporation Software Developer Intern Interview Questions, Process, and Tips

2Coding questions were there

Q1. Reverse string standard DSA
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Q2. Tapping rainwater standard DSA
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Moderate coding question

1 month long hackathon

Q1. Dsa round with live coding
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Round duration - 90 minutes
Round difficulty - Easy

There were 3 coding questions. All of them were pretty easy and solvable in less than 30 minutes. Some string and pattern matching + some number theory problems were there.

Q1. 
Arithmetic Expression Evaluation Problem Statement
You are provided with a string expression consisting of characters '+', '-', '*', '/', '(', ')' and digits '0' to '9', representing an arithmetic express...read more
Ans. 
Evaluate arithmetic expressions in infix notation with given operators and precedence rules.
• Parse the infix expression to postfix using a stack.

• Evaluate the postfix expression using a stack.

• Handle operators precedence and parentheses while evaluating.

• Ensure no division by zero cases and operands fit in 32-bit integer.
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Q2. 
Maximum Product Subarray Problem Statement
Given an array of integers, determine the contiguous subarray that produces the maximum product of its elements.
Explanation:
A subarray can be derived from th...read more
Ans. 
Find the contiguous subarray with the maximum product of elements in an array.
• Iterate through the array and keep track of the maximum and minimum product ending at each index.

• Update the maximum product by taking the maximum of current element, current element * previous maximum, and current element * previous minimum.

• Update the minimum product by taking the minimum of current element, current element * previous maximum...read more
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Q3. 
Angle Calculation Between Clock Hands
Given a specific time in hours and minutes, your task is to calculate the smallest possible angle between the hour hand and the minute hand of a clock.
Example:
Inp...read more
Ans. 
Calculate the smallest angle between the hour and minute hands of a clock given a specific time.
• Calculate the angle formed by the hour hand with respect to 12 o'clock position

• Calculate the angle formed by the minute hand with respect to 12 o'clock position

• Find the absolute difference between the two angles and take the minimum of the two possible angles

• Return the floor value of the calculated angle
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Round duration - 45 minutes
Round difficulty - Medium

This was a technical round. First after properly introducing ourselves(me and the interviewer), we started with the main interview. I was asked 2 questions, one DS and Algorithms and the other System Design question.

Q1. 
Problem Statement: Sibling Nodes
You are provided with a Binary Tree consisting of 'N' nodes, where each node holds an integer value. Your objective is to identify and list all nodes that do not possess a...read more
Ans. 
Identify and list nodes in a Binary Tree that do not have a sibling.
• Traverse the Binary Tree in level order and keep track of nodes without siblings.

• Check if each node has a sibling by comparing with its parent's other child.

• Output the values of nodes without siblings in ascending order.

• Handle cases where the root node is considered a sibling node.
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Q2. Design an elevator system for a single building with N floors.
Ans. 
Design an elevator system for a single building with N floors.
• Create a data structure to track the current floor of the elevator and the requested floors.

• Implement algorithms for elevator movement such as FIFO, SCAN, or LOOK.

• Consider factors like peak hours, weight capacity, and emergency situations.

• Include features like door open/close buttons, emergency stop button, and floor selection panel.
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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 - 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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