Dunzo Software Developer Intern Interview Questions, Process, and Tips

Round duration - 60 Minutes
Round difficulty - Medium

This was a DS/Algo round.
Timing was 4:00pm-5:00pm IST.
The interviewer was very friendly.
He asked for my introduction.

Q1. 
Asteroid Collision Problem Description
Given an array/list ASTEROIDS representing asteroids aligned in a row, each element's absolute value identifies the asteroid's size, while its sign indicates the dir...read more
Ans. 
Step 1 : I was able to think of a stack solution directly.
Step 2 : We have to keep track of asteroids that are moving in the right direction.
Step 3 : When we found an asteroid that is moving in the left direction then we will use the stack to check asteroids that will collide.
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Q2. 
Valid Parentheses Problem Statement
Given a string 'STR' consisting solely of the characters “{”, “}”, “(”, “)”, “[” and “]”, determine if the parentheses are balanced.
Input:
The first line contains an...read more
Ans. Valid Parenthesis
Make use of the stack. Traverse the string and push the current character in the stack if it is an opening brace else pop from the stack If it is the corresponding starting brace for current closing brace then move to the next character of the string otherwise return false.
 
If after complete traversal if the stack is empty then the string is balanced else it is not balanced.
 
Pseudo Code:
• Decla...read more
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Round duration - 60 Minutes
Round difficulty - Medium

Timing was 3:00pm-4:00pm IST
Interviewer was friendly
He asked for my introduction. We dry run the code for the question.

Q1. 
Word Break II Problem Statement
Given a non-empty string 'S' containing no spaces and a dictionary of non-empty strings, generate and return all possible sentences by adding spaces in the string 'S', such...read more
Ans. 
Step 1 : Was able to recognize that it was a question of backtracking.
Step 2 : Created a unordered hashmap to check if any string is part of dictionary or not.
Step 3 : Traverse the string in recursive manner. 
Step 4 : For each prefix, we check if it is part of dictionary or not. If it is part of dictionary then include this prefix string in answer otherwise include the next character in the string.
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Round duration - 60 Minutes
Round difficulty - Easy

This round contained two coding questions. I was also asked some basic android development questions as I had mentioned a couple of projects around android.

Q1. 
Convert Binary Tree to Mirror Tree Problem Statement
Given a binary tree, convert this binary tree into its mirror tree. A binary tree is a tree in which each parent node has at most two children. The mir...read more
Ans. 
I first clarified the doubts since the question was too vague in start.
Then I told that this problem can be solved with iterative or recursive approach, Interviewer told me to go ahead and code the recursive one. 
We discussed time complexity.
Then I implemented iterative one too.
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Q2. How would you implement undo and redo operations for MS Word?
Ans. 
I asked clarifying doubts to understand the exact scope. 
Then we discussed possible data structures.
And finally concluded that stack would be the best one. 
I didn't have to code this question.
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Round duration - 60 Minutes
Round difficulty - Medium

I was asked two coding questions, some questions around OOPs concepts and DBMS.

Q1. 
Left View of a Binary Tree
Given a binary tree, your task is to print the left view of the tree. The left view of a binary tree contains the nodes visible when the tree is viewed from the left side.
Inpu...read more
Ans. 
I gave the level order traversal approach.
Interviewer asked me to implement it. 
I discussed multiple ways to implement and went ahead with delimiter one.
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Q2. 
Trie Data Structure Implementation
Design and implement a Trie (Prefix Tree) which should support the following two operations:
1. Insert a word into the Trie. The operation is marked as 'insert(word)'.
2....read more
Ans. 
This was a straight forward implementation problem. We discussed everything about tries in detail.
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Round duration - 90 Minutes
Round difficulty - Medium

1. 90 min , can do anytime between a designated 4 hr window
2. was on Hackerrank, and I was familiar with the platform
3. had 3 coding questions

Q1. 
Bipartite Graph Problem Statement
Given an undirected graph of 'V' vertices (labeled 0, 1, ..., V-1) and 'E' edges, the task is to determine whether the graph is bipartite.
Explanation:
A bipartite grap...read more
Ans. DFS
The idea is very simple. To separate the vertices of the graph in two sets such that no two vertices of a set are connected, we will try to color the vertices of the graph using two colors only. 
If any of the adjacent vertices are of the same color, the graph is not bipartite. Else, it is bipartite. 
Note that, if there are more than 1 connected components in the graph, the graph will be bipartite if and on...read more
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Q2. 
Longest Common Subsequence Problem Statement
Given two strings STR1 and STR2, determine the length of their longest common subsequence.
A subsequence is a sequence that can be derived from another sequen...read more
Ans. Recursive Brute Force
The basic idea of this approach is to break the original problem into sub-problems. Let us assume we want to find the length of the longest common subsequence of “STR1” and “STR2” whose length is ‘N’ and ‘M’ respectively. 
 
Now, let us define a recursive function 
 
LCS(Int I, int J, string STR1, string STR2)
Which returns the length of the longest common subsequence of string STR1...read more
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Q3. 
Convert Array to Min Heap Task
Given an array 'ARR' of integers with 'N' elements, you need to convert it into a min-binary heap.
A min-binary heap is a complete binary tree where each internal node's va...read more
Ans. Heapify Algorithm
The idea is to follow a top-down approach. The given array does not necessarily represent a heap. In order to convert the input array to a heap, we will heapify the complete binary tree formed from the array in reverse order, i.e., from the rightmost element to the leftmost element. Heapify is defined as the process of converting a binary tree into a Heap data structure. We do not need to heapify the l...read more
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Round duration - 60 minutes
Round difficulty - Hard

With manager 
1. DS/algo
2. Networking
3, basic project stuff
4. Google meet
3. was in the afternoon

Q1. 
Wildcard Pattern Matching Problem Statement
Implement a wildcard pattern matching algorithm to determine if a given wildcard pattern matches a text string completely.
The wildcard pattern may include the...read more
Ans. Brute Force
We will try to explore all the possibilities using the recursion.
 
Let’s say we have a recursive function ‘REC’ who has two arguments IDX and IDY where IDX represents the index in the text string and IDY represents the index in pattern string and its return type is boolean. Initially, we will call the rec with IDX =  N and IDY = M where N is the size of the text string and M is the size of the patte...read more
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Q2. 
Left View of a Binary Tree Problem Statement
Given a binary tree, your task is to print the left view of the tree.
Example:
Input:
The input will be in level order form, with node values separated by a...read more
Ans. Recursive Approach
This problem can be solved through recursion.We will maintain max_level variable which will keep track of maxLevel and will pass current level in recursion as argument. Whenever we see a node whose current level is more than maxLevel then we will print that node as that will be first node for that current level. Also update maxLevel with current level.
Space Complexity: O(n)Explanation:
O(N), where ‘N’...read more
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