McKinsey & Company Software Developer Interview Questions and Answers

Round duration - 90 Minutes
Round difficulty - Medium

This round happened on the same day as JAM in the afternoon time. A slot of 20 minutes with respective timing was already sent to the selected students. Interview can’t be generalize as anything can happen over there and hence this was exclusively my experience. 
To have a quick judgement about the person, I believe nothing is better than throwing before him/her some puzzles (mathematical/ analytical/ programming problems) and see the approach. I received back-to-back 4 problems after a quick and brief introduction. The coding problems I got were way too easy (just basics: searching & mathematical). The harder part of this round was the puzzles (tricky, mathematical, related to probability). At last, I was asked a question on DBMS and the interviewer asked if I know JAVA.

Q1. 
Search an Element in a Sorted Array
Given a sorted array 'A' of 'N' integers, determine whether a number 'X' exists within this array for a series of queries. For each query, print 1 if 'X' exists in the ...read more
Ans. 
Search for a number in a sorted array and determine its existence for multiple queries.
• Use binary search algorithm to efficiently search for each query integer in the sorted array.

• For each query integer 'X', check if it exists in the array 'A' and output 1 if found, 0 otherwise.

• Ensure the array 'A' is sorted in non-decreasing order to apply binary search effectively.
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Clear basic programming fundamentals

Q1. All basic to advance concepts oops, SDLC, C3, asp.net, angular etc.
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Q1. When have you had a conflict with someone.
Ans. 
I had a conflict with a team member over project priorities.
• Miscommunication led to conflicting priorities

• Discussed the issue openly and found a compromise

• Learned the importance of clear communication in team projects
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Q2. Tell me you greatest project
Ans. 
Developed a web-based project management tool for tracking tasks and deadlines
• Used React for front-end development

• Implemented user authentication and authorization using JWT tokens

• Utilized Node.js and Express for back-end development

• Integrated MongoDB for database storage
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1 20 mark easy ques and 1 50 mark med ques, time : 1h 30 mins i guess

Q1. Common elemnts two list , oops
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Q2. Case study and oops sql
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Round duration - 90 minutes
Round difficulty - Medium

This test consists of two coding questions and some MCQ regarding computer fundamentals.

Q1. 
Kevin and His Cards Problem Statement
Kevin has two packs of cards. The first pack contains N cards, and the second contains M cards. Each card has an integer written on it. Determine two results: the tot...read more
Ans. 
Find total distinct card types and common card types between two packs of cards.
• Create a set to store distinct card types when combining both packs.

• Iterate through each pack and add card types to the set.

• Find the intersection of card types between the two packs to get common card types.
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Q2. 
Allocate Books Problem Statement
Given an array of integers arr, where arr[i] represents the number of pages in the i-th book, and an integer m representing the number of students, allocate all the books ...read more
Ans. 
Allocate books to students in a way that minimizes the maximum number of pages assigned to a student.
• Iterate through all possible allocations of books to students.

• Calculate the maximum number of pages assigned to a student for each allocation.

• Return the minimum of these maximums as the result.
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Round duration - 40 minutes
Round difficulty - Easy

It was a technical round that is based on DSA and computer fundamentals.

Q1. 
Reverse Linked List Problem Statement
Given a singly linked list of integers, return the head of the reversed linked list.
Example:
Initial linked list: 1 -> 2 -> 3 -> 4 -> NULL
Reversed link...read more
Ans. 
Reverse a singly linked list of integers and return the head of the reversed linked list.
• Iterate through the linked list and reverse the pointers to point to the previous node instead of the next node.

• Use three pointers - prev, current, and next to reverse the linked list in O(N) time and O(1) space complexity.

• Update the head of the reversed linked list as the last node encountered during the reversal process.
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Q2. 
Sort 0 1 2 Problem Statement
Given an integer array arr of size 'N' containing only 0s, 1s, and 2s, write an algorithm to sort the array.
Input:
The first line contains an integer 'T' representing the n...read more
Ans. 
Sort an array of 0s, 1s, and 2s in linear time complexity.
• Use three pointers to keep track of 0s, 1s, and 2s while traversing the array.

• Swap elements based on the values encountered to sort the array in-place.

• Time complexity should be O(N) and space complexity should be O(1).
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Challenging questions in mathematics.

A constructive discussion about the significance of various topics and additional aspects.

Q1. Questions based on Java , C++ , OOPs, cloud computing, one coding question, regarding previous projects, some behavioural questions.
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