Chargebee Senior Sdet Engineer Interview Questions and Answers

Easy level test can be cleared

Q1. Fibonacci sequence print
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Q2. Tell me about my self
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The coding round was for 1 hour. The problems asked were fairly easy to comprehend the logic.

This round was for an hour. In this round the test automation questions were asked, like finding the XPath and automating a simple feature such as search on make my trip or the calendar date select on mmt.

Q1. Optimize an existing system. The system currently makes an API call and stores data in its memory. When it tries to serve a request from another component it refers to the memory location by searching the ...read more
Ans. 
Implement a data structure like a hash table or a cache to optimize memory search.
• Use a hash table to store the data with keys as memory locations

• Implement a cache to store frequently accessed data for faster retrieval

• Consider using indexing or sorting techniques to optimize search operations
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Q1. What is your current salary?
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Q2. Questions about cultural fit.
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Q3. What is your expectation?
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DP,Binary Search, Graphs these are important topics.And focus on aptitude.

Tricky questions and need some time.

2 coding ques easy - medium level

Q1. Merge intervals, find second largest salary in sql
Ans. 
Merge intervals and find second largest salary in SQL
• For merging intervals, sort them by start time and then iterate through the intervals to merge overlapping ones

• For finding second largest salary, use the SQL query: SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees)
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Round duration - 90 Minutes
Round difficulty - Medium

It was a zoom call with a SDE-2 person, after 15 mins into my background he jumped directly to the questions
 

Q1. Binary Tree Zigzag Traversal
You have been given a Binary Tree of 'N' nodes, where the nodes have integer values. Your task is to print the zigzag traversal of the given tree.
Note:
In zigzag ord...read more
Ans. Brute force
We can use level order traversal (recursive) to explore all levels of the tree. Also, at each level nodes should be printed in alternating order. 
 
For example - First level of tree should be printed in left to right manner, Second level of tree should be printed in right to left manner, Third again in left to right order and so on.
 
So, we will use a Direction variable whose value will toggle a...read more
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Q2. Convert binary tree to mirror tree
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.
Mirror of a Tree: Mirr...read more
Ans. Recursive approach.
The idea is to traverse the binary tree and swap the left and right subtrees.
 
The steps are as follows:
 
1. Call mirror function as mirror(node->left)  to access the left subtree.
2. Call mirror function as mirror(node->right) to access the right subtree.
3. Swap left and right subtrees using:
• ‘TEMP’ = leftSubtree
• leftSubtree = rightSubtree
• rightSubtree = ‘TEMP’
Space Complexity: O(n)Explanation...read more
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Q3. Time to Burn Tree
You have been given a binary tree of 'N' unique nodes and a Start node from where the tree will start to burn. Given that the Start node will always exist in the tree, your task i...read more
Ans. Using BFS
The idea is to first create an undirected graph of the given binary tree and then doing a bfs traversal of the undirected graph starting from the start node. We will keep a variable ‘count’ that will be incremented at each level of bfs traversal. ‘count-1’ is the required time needed to burn the whole tree.
 
Algorithm
 
• Initialize an unordered map ‘M’ that maps from integer to array of integers that sto...read more
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Round duration - 90 Minutes
Round difficulty - Medium

Again this was a Problem Solving round taken by a SDE-2 

Q1. Topological Sort
A Directed Acyclic Graph (DAG) is a directed graph that contains no cycles.
Topological Sorting of DAG is a linear ordering of vertices such that for every directed edge from vertex ‘u’...read more
Ans. Modify Depth First Search
In the Depth First Search (DFS), we start from a vertex, we first print it and then recursively call DFS for its adjacent vertices. In topological sorting, we use a  stack. We don’t print the vertex immediately, we first recursively call topological sorting for all its adjacent vertices, then push it to a stack. Finally, print contents of the stack. Note that a vertex is pushed to stack on...read more
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Round duration - 100 Minutes
Round difficulty - Hard

This round was with a SDE-3(Principal Engineer)

Q1. Trailing Zeros in Factorial
You are given an integer N, you need to find the number of trailing zeroes in N! (N factorial).
Note:
1. Trailing zeros in a number can be defined as the number of continuous...read more
Ans. Find the factorial of the number
• Calculate the factorial of N.
• Initialise FACT = 1 to store factorial of N, iterate 1 <= i <= N and do FACT = FACT * i.
• Count the number of trailing zeroes in FACT. Initialise ZEROES = 0.
• Repeatedly divide the FACT by 10, if the remainder is 0, increase ZEROES by 1. If the remainder > 0, stop and return ZEROES.
Space Complexity: O(1)Explanation:
O(1), as we are using constant extra m...read more
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Round duration - 90 Minutes
Round difficulty - Hard

This round was scheduled with a SDE-3/SDE-4(Senior Principal Engineer):
He directly started with questions after my introduction of 5mins
 

Round duration - 90 Miinutes
Round difficulty - Medium

Discussion with Hiring Manager
 

Q1. Loot Houses
A thief wants to loot houses. He knows the amount of money in each house. He cannot loot two consecutive houses. Find the maximum amount of money he can loot.
Input Format :
The first line of...read more
Ans. Recursive Approach
Suppose that the robber is at the ith house. The robber has two options:
• If he decides to rob this house, then he cannot rob the next house, so he’ll have to go to the house after that.
• If he decides not to rob this house, he has no restriction over choosing the next house.
You will follow the same for the rest of the houses. Thus, if maxLoot(i) is the maximum loot possible when we’re at the ith house, t...read more
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Round duration - 75 Minutes
Round difficulty - Easy

This round was with VP in Redwood City , it was scheduled around 11:00 pm IST