Dunzo Software Developer Intern Interview Questions, Process, and Tips

Round duration - 90 mintues
Round difficulty - Easy

Nice environment everything went good.

Q1. 
Sum of LCM Problem Statement
Given an integer 'N', calculate and print the sum of the least common multiples (LCM) for each integer from 1 to N with N.
The sum is represented as:
LCM(1, N) + LCM(2, N) + ....read more
Ans. 
Calculate and print the sum of least common multiples (LCM) for each integer from 1 to N with N.
• Iterate from 1 to N and calculate LCM of each pair with N

• Sum up all the calculated LCMs to get the final result

• Implement a function to calculate LCM of two numbers
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Q2. 
Vertical Order Traversal Problem Statement
Given a binary tree, return the vertical order traversal of the values of the nodes in the tree.
In a vertical order traversal, for each node at position (X, Y)...read more
Ans. 
Vertical order traversal of binary tree is obtained by running a vertical line from -∞ to +∞ and adding node values in top to bottom order, sorted by decreasing Y coordinates.
• Implement a function to perform vertical order traversal of a binary tree

• Maintain a map to store nodes at each vertical level

• Sort the nodes at each level by their Y coordinates in decreasing order

• Handle cases where two nodes share the same positio
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Round duration - 90 minutes
Round difficulty - Hard

It was a tough round focus on the key concepts

Q1. 
Stack with getMin Operation
Create a stack data structure that supports not only the usual push and pop operations but also getMin(), which retrieves the minimum element, all in O(1) time complexity witho...read more
Ans. 
Implement a stack with getMin operation in O(1) time complexity without using extra space.
• Use two stacks - one to store the actual elements and another to store the minimum values encountered so far.

• When pushing an element, check if it is smaller than the current minimum and if so, push it onto the minimum stack.

• When popping an element, check if it is the current minimum and if so, pop from the minimum stack as well.

• Fo...read more
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Round duration - 90 mintues
Round difficulty - Medium

Goes good no problem at all exam is between 10 to 11:30.

Q1. 
Game of Dominoes Problem Statement
Rafiq loves to play with piles of dominoes, especially when they are of equal heights. His father gifted him 'N' piles of dominoes, each with a positive number of stacke...read more
Ans. 
Calculate minimum cost to make consecutive windows of domino piles equal in height.
• Iterate through each window of size 'K' and calculate the minimum cost to make all piles in that window equal in height.

• Keep track of the running sum of domino heights in each window to minimize cost.

• Return the minimum cost for each window as the output.
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Q2. 
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 hash set.

• If the complement exists, add the pair (current element, complement) to the result list.

• Sort the result list based on the first element of each pair, and then based on the second element if the first elements are eq
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Round duration - 90 minutes
Round difficulty - Hard

Goes good no problem at all exam at same time between 10 to 11:30.

Q1. What problems did you face in your project and how did you deal with them?
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Q2. 
Ninja and Sorted Arrays Problem
You are given two sorted integer arrays, ARR1 and ARR2, with sizes M and N, respectively. Merge these arrays into ARR1 as a single sorted array. Assume ARR1 has a size equa...read more
Ans. 
Merge two sorted arrays into one sorted array in place.
• Iterate from the end of both arrays and compare elements, placing the larger element at the end of ARR1

• Continue this process until all elements from ARR2 are merged into ARR1

• Ensure to handle cases where one array is fully merged before the other
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Round duration - 90 minutes
Round difficulty - Medium

There were a total of three questions of 100, 200, and 300 points respectively. Partial points were given if partial tests got passed for any problem. The Codesignal environment was similar to Hackerrank, so not much different. I think the test was held in the afternoon time.

Q1. 
Game of Stones Problem Statement
Two players, 'Ale' and 'Bob', are playing a game with a pile of stones. Your task is to determine the winner if both play optimally.
Rules of the Game:
1. On each turn, ...read more
Ans. 
Determining the winner of a game where two players take turns to remove stones from a pile based on certain rules.
• Implement a recursive function to simulate the game where each player makes the optimal move.

• Check if the current player can take any stones, if not, the other player wins.

• Return 'Ale' if 'Ale' wins, otherwise return 'Bob'.
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Q2. 
Return Subsets Sum to K Problem Statement
Given an integer array 'ARR' of size 'N' and an integer 'K', return all the subsets of 'ARR' which sum to 'K'.
Explanation:
A subset of an array 'ARR' is a tupl...read more
Ans. 
Given an array and an integer, return all subsets that sum to the given integer.
• Use backtracking to generate all possible subsets of the array.

• Keep track of the current subset and its sum while backtracking.

• If the sum of the subset equals the target sum, add it to the result.

• Recursively explore both including and excluding the current element in the subset.

• Sort the elements in each subset to ensure increasing order of
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Round duration - 60 minutes
Round difficulty - Medium

This round was a video call round held on Zoom and the Codesignal platform was to be used for coding the problems. The round started with the interviewer giving a small introduction about him and then asking me to introduce myself.

Q1. 
Rotting Oranges Problem Statement
You are given a grid containing oranges where each cell of the grid can contain one of the three integer values:
• 0 - representing an empty cell
• 1 - representing a fre...read more
Ans. 
Find the minimum time required to rot all fresh oranges in a grid.
• Use Breadth First Search (BFS) to simulate the rotting process of oranges.

• Track the time taken to rot all oranges and return -1 if any fresh oranges remain.

• Handle edge cases such as empty grid, no fresh oranges, or no rotten oranges.

• Update the status of adjacent fresh oranges to rotten oranges in each iteration.
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Q2. 
Find Indices for Local Minima and Maxima
Given an integer array arr of size N, your task is to determine all indices of local minima and local maxima within the array. Return these indices in a 2-D list, ...read more
Ans. 
Find indices of local minima and maxima in an integer array.
• Iterate through the array and compare each element with its neighbors to find local minima and maxima.

• Consider corner elements separately by comparing with only one neighbor.

• Return the indices of local minima and maxima in a 2-D list.
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Round duration - 60 minutes
Round difficulty - Medium

The setup was exactly similar to the first interview round. The interviewer was very friendly. My advice will be to see the interviewer as a team mate and think you have to solve the question together with him. Don't panic and start speaking out what observations you can make about the problem.

Q1. 
Sort By Kth Bit
Given an array or list ARR of N positive integers and an integer K, your task is to rearrange all elements such that those with the K-th bit (considering the rightmost bit as '1st' bit) eq...read more
Ans. 
Rearrange elements in an array based on the K-th bit being 0 or 1.
• Iterate through the array and separate elements based on the K-th bit being 0 or 1.

• Maintain the relative order of elements within each group.

• Combine the two groups to get the final rearranged array.

• Time complexity can be optimized to linear time by using bitwise operations.

• Example: For ARR = {1, 2, 3, 4} and K = 1, output should be {2, 4, 1, 3}.
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Round duration - 60 minutes
Round difficulty - Medium

It was already night time till this interview started because all the three interview rounds were held on the same day. This was not a DS+Algorithms round. He first asked me to introduce myself. So I started by telling what all I have done in my college up till now and then I told him about my internship experience at myKaarma which just ended few days back. There was around 10-15 minutes discussion on what I was working on in my intern project.

Graphs ,arrays , Hashmaps and Heaps

Q1. Graphs related dfs
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Q2. Changes on graph structure
Ans. 
Changes on graph structure involve adding, removing, or modifying nodes and edges.
• Adding a new node to the graph

• Removing an existing node from the graph

• Modifying the weight of an edge in the graph
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Round duration - 90 minutes
Round difficulty - Easy

This round had 2 coding problems and we had to code it on hackerearth only.
The use of Outside IDE was forbidden.
The timing of test was 12:00 PM to 1:30 PM.

Q1. 
Meeting Rescheduling Challenge
Ninja is tasked with organizing a meeting in an office that starts at time ‘0’ and ends at time ‘LAST’. There are ‘N’ presentations scheduled with given start and end times....read more
Ans. 
Reschedule at most K presentations to maximize gap without overlap.
• Iterate through presentations and calculate the gaps between them

• Sort presentations by end time and reschedule K presentations to maximize gap

• Return the longest gap achieved
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Q2. 
Total Unique Paths Problem Statement
You are located at point ‘A’, the top-left corner of an M x N matrix, and your target is point ‘B’, the bottom-right corner of the same matrix. Your task is to calcula...read more
Ans. 
Calculate total unique paths from top-left to bottom-right corner of a matrix by moving only right or down.
• Use dynamic programming to solve this problem efficiently.

• Create a 2D array to store the number of unique paths for each cell.

• Initialize the first row and first column with 1 as there is only one way to reach them.

• For each cell, the number of unique paths is the sum of paths from the cell above and the cell to the...read more
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Round duration - 90 minutes
Round difficulty - Medium

This round was coding round with discussion .
The interviewer tried to trick the questions and wanted to test how we respond if something is asked out of preparation.
The code we ran on Google Docs was checked on Online IDE if it ran for sample inputs.
Timing : 12:00 PM to 1:30 PM

Q1. 
Minimum Operations to Connect a Graph
You are given a graph with 'N' vertices labeled from 1 to 'N' and 'M' edges. In one operation, you can shift an edge from being between two directly connected vertice...read more
Ans. 
Determine the minimum number of operations to connect a graph by shifting edges between disconnected vertices.
• Use a disjoint set union (DSU) data structure to keep track of connected components.

• Count the number of connected components in the graph.

• The minimum number of operations required is equal to the number of connected components minus 1.
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Q2. 
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 on the board.

• Create a mapping of each cell to its corresponding row and column on the board.

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

• Handle the case where the last cell is unreachable by returning -1.

• Optimize ...read more
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Round duration - 75 minutes
Round difficulty - Hard

This was a problem solving round and lasted for 75 minutes. The interviewer gave me a very complicated question.
The round was held on Google Meet and I was supposed to tell him the approach and write code on shared Google Docs.

Q1. 
XOR Query Problem Statement
Assume you initially have an empty array called ARR. You are required to return the updated array after executing Q number of queries on this array.
There are two types of que...read more
Ans. 
Implement a function to update an array based on XOR queries.
• Create an empty array to store the elements.

• Iterate through each query and update the array accordingly.

• Use bitwise XOR operation to update the elements.

• Ensure to handle both types of queries - insert and XOR operation.
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Round duration - 45 minutes
Round difficulty - Medium

The nature of the interviewer was very kind. The test was proctored, our webcam and mic were on, and shared my screen.

Q1. 
Diagonal Traversal of a Binary Tree
Given a binary tree of integers, find its diagonal traversal. Refer to the example for clarification on diagonal traversal.
Example:
Explanation:
Consider lines at a...read more
Ans. 
Diagonal traversal of a binary tree involves printing nodes at the same diagonal in a specific order.
• Traverse the tree in a diagonal manner, starting from the root node and moving towards the right child and then the left child.

• Use a queue to keep track of nodes at each level of the tree.

• Print the nodes in each diagonal level in the order they are encountered.

• Example: For the given binary tree, the diagonal traversal w
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Q2. 
Binary Tree Diameter Problem Statement
You are given a Binary Tree, and you need to determine the length of the diameter of the tree.
The diameter of a binary tree is the length of the longest path betwe...read more
Ans. 
The task is to find the diameter of a binary tree, which is the longest path between any two nodes in the tree.
• Traverse the tree to find the longest path between any two nodes.

• Keep track of the maximum diameter found during traversal.

• The diameter may not necessarily pass through the root node.

• Consider both left and right subtrees while calculating the diameter.

• Example: For input '1 2 3 4 -1 5 6 -1 7 -1 -1 -1 -1 -1 -1',
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Round duration - 45 Minutes
Round difficulty - Medium

The nature of the interviewer was very kind, helped me when I stuck. The test was proctored, our webcam and mic were on, and shared my screen.

Q1. 
Next Greater Element Problem Statement
Given a list of integers of size N, your task is to determine the Next Greater Element (NGE) for every element. The Next Greater Element for an element X is the firs...read more
Ans. 
Find the Next Greater Element for each element in a list of integers.
• Iterate through the list of integers from right to left.

• Use a stack to keep track of elements for which the Next Greater Element is not yet found.

• Pop elements from the stack until a greater element is found or the stack is empty.

• Assign the Next Greater Element as the top element of the stack or -1 if the stack is empty.
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Q2. 
Subset Sum Equal To K Problem Statement
Given an array/list of positive integers and an integer K, determine if there exists a subset whose sum equals K.
Provide true if such a subset exists, otherwise r...read more
Ans. 
Given an array of positive integers and an integer K, determine if there exists a subset whose sum equals K.
• Use dynamic programming to solve this problem efficiently.

• Create a 2D array to store if a subset sum is possible for each element and target sum.

• Iterate through the array and update the 2D array based on the current element and target sum.

• Check if the 2D array contains true for the target sum at the end.
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Round duration - 45 Minutes
Round difficulty - Medium

The nature of the interviewer was very kind, helped me when I stuck. The test was proctored, our webcam and mic were on, and shared my screen.

Q1. 
Buy and Sell Stock Problem Statement
Imagine you are Harshad Mehta's friend, and you have been given the stock prices of a particular company for the next 'N' days. You can perform up to two buy-and-sell ...read more
Ans. 
The task is to determine the maximum profit that can be achieved by performing up to two buy-and-sell transactions on a given set of stock prices.
• Iterate through the array of stock prices and keep track of the maximum profit that can be achieved with two transactions.

• Maintain variables to store the maximum profit after the first buy-sell, the maximum profit after the second buy-sell, and the minimum price encountered s...read more
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