Dunzo Software Developer Intern Interview Questions and Answers

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. 
Determine the state of asteroids after collisions occur.
• Iterate through the array of asteroids and simulate collisions between adjacent asteroids.

• Use a stack to keep track of remaining asteroids after collisions.

• Handle cases where asteroids moving in opposite directions collide and destroy each other.

• Handle cases where asteroids moving in the same direction do not 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. 
The task is to determine if a given string consisting of parentheses is balanced or not.
• Use a stack data structure to keep track of opening parentheses

• Iterate through the string and push opening parentheses onto the stack and pop when encountering a closing parenthesis

• If at the end the stack is empty, the string is balanced, otherwise it is not
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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. 
Given a string and a dictionary, generate all possible sentences by adding spaces between words from the dictionary.
• Use backtracking to generate all possible sentences by recursively adding words from the dictionary to the current sentence.

• Check if the current substring of the input string exists in the dictionary, if so, add it to the current sentence and continue recursively.

• When the entire input string is processed,...read more
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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. 
The task is to determine whether a given undirected graph is bipartite or not.
• Create a function to check if the graph can be colored using two colors without any adjacent vertices sharing the same color.

• Use graph coloring algorithms like BFS or DFS to determine if the graph is bipartite.

• Check for odd-length cycles in the graph, as a bipartite graph cannot have odd-length cycles.

• Consider using a boolean array to keep tr...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. 
The problem involves finding the length of the longest common subsequence between two given strings.
• Use dynamic programming to solve the problem efficiently.

• Create a 2D array to store the lengths of common subsequences of substrings.

• Iterate through the strings to fill the array and find the length of the longest common subsequence.

• Return the length of the longest common subsequence for each test case.
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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. 
Convert the given array into a min-binary heap by following min-heap properties.
• Iterate through the array and heapify each node starting from the last non-leaf node to the root.

• For each node, compare it with its children and swap if necessary to maintain min-heap property.

• Continue this process until the entire array satisfies the min-heap property.
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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. 
Implement a wildcard pattern matching algorithm to determine if a given wildcard pattern matches a text string completely.
• Create a dynamic programming matrix to store intermediate results

• Handle cases for '?' and '*' characters separately

• Check if the characters match or '*' can be used to match any sequence of characters
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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. 
Print the left view of a binary tree given in level order form.
• Traverse the tree level by level and print the first node of each level (leftmost node)

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

• Time complexity should be O(n) where n is the number of nodes in the tree
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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. 
Convert a binary tree into its mirror tree by interchanging left and right children of non-leaf nodes.
• Traverse the binary tree in a recursive manner and swap the left and right children of each non-leaf node.

• Use a temporary variable to swap the children of each node.

• Ensure to handle cases where a node may have only one child or no children.

• Implement the function to convert the given binary tree to its mirror tree in pl...read more
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Q2. How would you implement undo and redo operations for MS Word?
Ans. 
Implementing undo and redo operations for MS Word
• Maintain a stack for undo operations and another stack for redo operations

• Whenever a change is made, push the previous state onto the undo stack

• When undo is triggered, pop the state from undo stack and push it onto redo stack

• When redo is triggered, pop the state from redo stack and push it onto undo stack

• Ensure to update the document state accordingly after each undo or ...read more
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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. 
Print the left view of a binary tree, containing nodes visible from the left side.
• Traverse the tree level by level, keeping track of the leftmost node at each level

• Use a queue for level order traversal and a map to store the leftmost nodes

• Print the values of leftmost nodes stored in the map as the left view of the tree
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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. 
Implement a Trie data structure supporting insert and search operations efficiently.
• Implement a Trie class with insert and search methods.

• Use a nested class Node to represent each node in the Trie.

• For insert operation, iterate through each character in the word and create nodes as needed.

• For search operation, traverse the Trie based on the characters in the word to check for existence.

• Return 'TRUE' if the word is found...read more
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