Dunzo SDE-2 Interview Questions, Process, and Tips

Round duration - 60 minutes
Round difficulty - Easy

Timing: evening
Environment: Online round took at home

Q1. 
Smallest Subarray with K Distinct Elements Problem
Given an array A consisting of N integers, find the smallest subarray of A that contains exactly K distinct integers.
Input:
The first line contains tw...read more
Ans. 
Find the smallest subarray with exactly K distinct integers in an array.
• Use a sliding window approach to keep track of the subarray with K distinct integers.

• Use a hashmap to store the frequency of each integer in the current window.

• Update the window size based on the number of distinct integers found.

• Keep track of the smallest subarray meeting the criteria.

• Return the starting and ending indices of the smallest subarray
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Round duration - 90 minutes
Round difficulty - Medium

Machine coding round

Round duration - 60 minutes
Round difficulty - Medium

Q1. 
Rat In a Maze Problem Statement
Given a N * N maze with a rat placed at position MAZE[0][0], find and print all possible paths for the rat to reach its destination at MAZE[N-1][N-1]. The rat is allowed to...read more
Ans. 
The problem involves finding all possible paths for a rat to reach its destination in a maze.
• Use backtracking to explore all possible paths in the maze.

• Mark visited cells to avoid revisiting them.

• Return the path once the destination is reached.

• Handle edge cases like blocked cells and out-of-bounds movements.
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Round duration - 60-90 minutes
Round difficulty - Medium

Round duration - 60 minutes
Round difficulty - Medium

Hiring Manager round

Round duration - 60 minutes
Round difficulty - Medium

It was a telephonic interview at 10 in the morning. Interviewer seemed cool.

Q1. 
Best Insert Position for a Target in a Sorted Array
You are provided with a sorted array A of length N consisting of distinct integers and a target integer M. Your task is to determine the position where ...read more
Ans. 
Find the best insert position for a target in a sorted array to maintain order.
• Use binary search to find the correct position for the target integer in the sorted array.

• If the target is already present in the array, return its index.

• Maintain the sorted order of the array after inserting the target integer.

• Handle edge cases like empty array or target being smaller than the first element or larger than the last element.
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Round duration - 60 minutes
Round difficulty - Medium

The interview was in the morning at 10 AM in the office meeting room.

Q1. 
House Robber Problem Statement
Mr. X is a professional robber with a plan to rob houses arranged in a circular street. Each house has a certain amount of money hidden, separated by a security system that ...read more
Ans. 
House Robber problem - find maximum amount of money Mr. X can rob without triggering alarm in circular street.
• Use dynamic programming to keep track of maximum money robbed at each house.

• Consider two cases - robbing the first house and not robbing the first house.

• Handle circular arrangement by considering the first and last houses separately.

• Return the maximum amount of money that can be robbed without triggering the al
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Round duration - 60 minutes
Round difficulty - Medium

The interview was at 11 AM in the meeting office.

Q1. 
Running Median Problem
Given a stream of integers, calculate and print the median after each new integer is added to the stream.
Output only the integer part of the median.
Example:
Input:
N = 5  
Stre...read more
Ans. 
Calculate and print the median after each new integer is added to the stream.
• Use a min heap to store the larger half of the numbers and a max heap to store the smaller half of the numbers.

• Keep the two heaps balanced by ensuring the size difference is at most 1.

• If the total number of elements is odd, the median is the top element of the larger heap. If even, it's the average of the tops of both heaps.
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Round duration - 60 minutes
Round difficulty - Medium

The interview was at 1 AM.

Round duration - 60 minutes
Round difficulty - Easy

The meeting was at 2 PM in the office meeting room.

Round duration - 60 minutes
Round difficulty - Easy

10 AM

Q1. Can you provide a deeper discussion about all the projects you completed in your previous company?
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Round duration - 1hour
Round difficulty - Hard

Q1. 
Snake and Ladder Problem Statement
Given a 'Snake and Ladder' board with N rows and N columns, where positions are numbered from 1 to (N*N) starting from the bottom left, alternating direction each row, f...read more
Ans. 
Find the minimum number of dice throws required to reach the last cell on a 'Snake and Ladder' board.
• Use Breadth First Search (BFS) algorithm to find the shortest path from start to end cell.

• Keep track of visited cells and the number of dice throws required to reach each cell.

• Consider the presence of snakes and ladders while calculating the next possible moves.

• Return the minimum number of dice throws to reach the last
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Round duration - 1hour
Round difficulty - Hard

Q1.  Stack using queue
Mvvm architecture
Ans. 
Implement a stack using a queue in MVVM architecture
• Use two queues to simulate a stack

• Push operation: Enqueue the element to queue 1

• Pop operation: Dequeue all elements from queue 1 to queue 2, dequeue the last element from queue 2 (which is the top of the stack)

• Ensure proper synchronization between the two queues

• Example: Push(1), Push(2), Pop() should return 2
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Round duration - 1hour
Round difficulty - Easy

Round duration - 60 minutes
Round difficulty - Medium

It was a problem solving round where a hackerrank link was given containing 2 questions.
You have to solve them within 90 minutes.
I was asked to solve it within a week.

Q1. 
Find Distinct Palindromic Substrings
Given a string 'S', identify and print all distinct palindromic substrings within it. A palindrome reads the same forwards and backwards. For example, 'bccb' is a pali...read more
Ans. 
Given a string, find and print all distinct palindromic substrings within it.
• Iterate through all possible substrings of the input string

• Check if each substring is a palindrome

• Store distinct palindromic substrings in a set and then sort them before printing
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Round duration - 60 minutes
Round difficulty - Easy

2 questions was asked by the interviewer. You have to clearly explain your approach and write a working solution. He even asked me to run on some additional test cases

Q1. 
Job Sequencing Problem Statement
You are provided with a N x 2 2-D array called Jobs consisting of N jobs. In this array, Jobs[i][0] represents the deadline of the i-th job, while Jobs[i][1] indicates the...read more
Ans. 
Maximize profit by scheduling jobs within their deadlines.
• Sort the jobs based on their profits in descending order.

• Iterate through the sorted jobs and schedule them based on their deadlines.

• Keep track of the maximum profit achievable by scheduling jobs within their deadlines.
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Q2. 
Partition Equal Subset Sum Problem
Given an array ARR consisting of 'N' positive integers, determine if it is possible to partition the array into two subsets such that the sum of the elements in both sub...read more
Ans. 
The problem is to determine if it is possible to partition an array into two subsets with equal sum.
• Use dynamic programming to solve this problem efficiently.

• Create a 2D array to store the subset sum possibilities.

• Check if the total sum of the array is even before attempting to partition.

• Iterate through the array and update the subset sum array accordingly.

• Return true if the subset sum array contains a sum equal to hal
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Round duration - 60 minutes
Round difficulty - Easy

I was asked 1 system design question. The question was to design an online multiplayer game which can be scaled for more than 10 million users. 
The interviewer helped me to collect requirement and also helped me in choosing different low latency protocol to communicate between client and server.

Round duration - 60 minutes
Round difficulty - Medium

The interviewer asked few sql based questions and asked me to write the solution.
He also gave 1 problem solving question.

Q1. Can you explain the different types of joins in SQL and how to calculate the average of all values from a given table?
Ans. 
Different types of joins in SQL and calculating average of values from a table.
• Types of joins: INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN

• To calculate average: Use AVG() function in SQL

• Example: SELECT AVG(column_name) FROM table_name
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Round duration - 1 hour
Round difficulty - Medium

This was coding round and was conducted on Google meet with code link shared. Their were 2 interviewers that gave questions and later ran code on sample test cases.

Q1. 
Print Permutations - String Problem Statement
Given an input string 'S', you are tasked with finding and returning all possible permutations of the input string.
Input:
The first and only line of input ...read more
Ans. 
Return all possible permutations of a given input string.
• Use recursion to generate all possible permutations of the input string.

• Swap characters at different positions to generate permutations.

• Handle duplicate characters by skipping swapping if the characters are the same.
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Q2. 
Find the Kth Row of Pascal's Triangle Problem Statement
Given a non-negative integer 'K', determine the Kth row of Pascal’s Triangle.
Example:
Input:
K = 2
Output:
1 1
Input:
K = 4
Output:
1 4 6 ...read more
Ans. 
The task is to find the Kth row of Pascal's Triangle given a non-negative integer K.
• Create an array to store the elements of the Kth row of Pascal's Triangle.

• Use the formula C(n, k) = C(n-1, k-1) + C(n-1, k) to calculate the elements.

• Return the array as the output.
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Round duration - 2 hours
Round difficulty - Medium

This was a Machine Coding Round/LLD round followed by HLD round which was taken by Video Conferencing and Screen Sharing.

Round duration - 75 minutes
Round difficulty - Medium

This was the last round. This was HM round followed by the HR round.

Round duration - 60 Minutes
Round difficulty - Medium

Timing was around 11 am
Environment was great, it intrigued me to join Blinkit.

Q1. 
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.
• Sort the array in non-decreasing order.

• Use two pointers approach to find pairs with sum equal to 'S'.

• Return pairs in sorted order based on first value, with smaller second value coming first.
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Round duration - 60 Minutes
Round difficulty - Medium

Timing 11 am
Interviewer had good knowledge

Q1. Can you explain the activity lifecycle in Android development?
Ans. 
Activity lifecycle in Android development involves various states like onCreate, onStart, onResume, onPause, onStop, onDestroy.
• Activity is created with onCreate() method

• Activity becomes visible with onStart() and onResume() methods

• Activity goes into background with onPause() method

• Activity is stopped with onStop() method

• Activity is destroyed with onDestroy() method
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Q2. Can you explain the fragment lifecycle in Android development?
Ans. 
Fragment lifecycle in Android involves various states like created, started, resumed, paused, stopped, and destroyed.
• Fragments are created using the onCreateView() method.

• Fragments go through states like created, started, resumed, paused, stopped, and destroyed based on user interactions and system events.

• Fragment lifecycle methods include onCreate(), onStart(), onResume(), onPause(), onStop(), and onDestroy().
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Q3. Can you explain the MVVM pattern?
Ans. 
MVVM is a design pattern that separates the user interface from the business logic and data model.
• MVVM stands for Model-View-ViewModel

• Model represents the data and business logic

• View represents the UI components

• ViewModel acts as an intermediary between the Model and View, handling user input and updating the Model

• MVVM promotes separation of concerns and easier unit testing
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Round duration - 30 Minutes
Round difficulty - Easy

This round is cultural fit round

Round duration - 60 Minutes
Round difficulty - Medium

Anytime

Q1. 
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. 
The task is to sort an array of 0s, 1s, and 2s in increasing order.
• Use a three-pointer approach to partition the array into three sections: 0s, 1s, and 2s.

• Initialize three pointers: low, mid, and high. low points to the start of the array, mid points to the current element being processed, and high points to the end of the array.

• While mid <= high, if ARR[mid] is 0, swap ARR[low] and ARR[mid], increment low and mid. If
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Q2. 
Connect Ropes with Minimum Cost
Given 'N' ropes, each having different lengths, your task is to connect these ropes into one single rope. The cost to connect two particular ropes is equal to the sum of th...read more
Ans. 
The task is to connect N ropes into one rope with minimum cost.
• Sort the array of rope lengths in ascending order.

• Initialize a variable to keep track of the total cost.

• While there are more than one rope, take the two shortest ropes and connect them.

• Add the cost of connecting the two ropes to the total cost.

• Replace the two shortest ropes with the connected rope.

• Repeat the above steps until only one rope remains.

• Return th
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Round duration - 60 Minutes
Round difficulty - Medium

Q1. 
Maximum Subarray Sum Problem Statement
Given an array ARR consisting of N integers, your goal is to determine the maximum possible sum of a non-empty contiguous subarray within this array.
Example of Sub...read more
Ans. 
The task is to find the maximum possible sum of a non-empty subarray of an array.
• Iterate through the array and keep track of the maximum sum encountered so far

• If the current element is greater than the sum so far, start a new subarray

• If the current element plus the sum so far is greater than the maximum sum, update the maximum sum

• Return the maximum sum
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Q2. 
Diameter of a Binary Tree Problem Statement
Given a binary tree, return the length of its diameter. The diameter of a binary tree is defined as the length of the longest path between any two nodes in the ...read more
Ans. 
The diameter of a binary tree is the length of the longest path between any two end nodes in the tree.
• The diameter of a binary tree can be calculated by finding the maximum of the following three values: 1) the diameter of the left subtree, 2) the diameter of the right subtree, and 3) the longest path that passes through the root node.

• To find the diameter of a binary tree, we can use a recursive approach where we calcu...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round was more aroung sytem design and my past work experience.

Q1. Can you describe the system design for a platform like BookMyShow and the questions that were raised during the discussion?
Ans. 
Design a bookmyshow system
• Design a system to book and manage movie tickets

• Consider features like seat selection, payment, and ticket cancellation

• Include user authentication and authorization

• Implement a database to store movie and theater information

• Consider scalability and performance of the system
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Round duration - 30 Minutes
Round difficulty - Easy

This is non-tech round.They just want to check your nature ,attitude and team work skills.

Q1. Why do you want to leave your current job and what are your thoughts on the CTC being offered?
Ans. 
I want to leave my current job for better growth opportunities and a more challenging role.
• Seeking new challenges and opportunities for professional growth

• Looking for a role that aligns better with my skills and interests

• Desire to work in a more dynamic and innovative environment

• Seeking better compensation and benefits

• Wanting to expand my knowledge and skills in a different domain
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