Housing.com Front end Engineer Interview Questions, Process, and Tips

Round duration - 45 minutes
Round difficulty - Easy

This was a test where 2 coding questions were to be solved in 45 minutes.

Q1. 
Excel Column Number Conversion
Given a column title as it appears in an Excel sheet, your task is to return its corresponding column number.
Example:
Input:
S = "AB"
Output:
28
Explanation:
The seq...read more
Ans. 
Convert Excel column title to corresponding column number.
• Iterate through the characters in the input string from right to left

• Calculate the value of each character based on its position and multiply by 26^index

• Sum up the values to get the final column number
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Q2. 
Check Permutation Problem
Determine if two given strings, str1 and str2, are permutations of each other.
Explanation:
Two strings are permutations of each other if the characters of one string can be re...read more
Ans. 
Check if two strings are permutations of each other.
• Create character frequency maps for both strings.

• Compare the frequency maps to check if they are permutations.

• Handle edge cases like empty strings or strings of different lengths.
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Round duration - 60 minutes
Round difficulty - Easy

It comprised of general aptitude questions and two coding questions. It was an offline test.

Q1. 
N Queens Problem
Given an integer N, find all possible placements of N queens on an N x N chessboard such that no two queens threaten each other.
Explanation:
A queen can attack another queen if they ar...read more
Ans. 
The N Queens Problem involves finding all possible placements of N queens on an N x N chessboard where no two queens threaten each other.
• Use backtracking algorithm to explore all possible configurations.

• Keep track of rows, columns, and diagonals to ensure queens do not attack each other.

• Generate and print valid configurations where queens are placed safely.

• Consider constraints and time limit for efficient solution.

• Exam...read more
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Q2. 
Sort 0 1 2 Problem Statement
Given an integer array arr of size 'N' containing only 0s, 1s, and 2s, write an algorithm to sort the array.
Input:
The first line contains an integer 'T' representing the n...read more
Ans. 
Sort an integer array containing only 0s, 1s, and 2s in linear time complexity.
• Use three pointers to keep track of the positions of 0s, 1s, and 2s in the array.

• Iterate through the array and swap elements based on the values encountered.

• Achieve sorting in a single scan over the array without using any extra space.
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Round duration - 60 minutes
Round difficulty - Easy

After having a technical discussion about my CV. He gave me two questions to code.

Q1. 
Ninja and Substrings Problem Statement
Ninja has to determine all the distinct substrings of size two that can be formed from a given string 'STR' comprising only lowercase alphabetic characters. These su...read more
Ans. 
Find all unique contiguous substrings of size two from a given string.
• Iterate through the string and extract substrings of size two

• Use a set to store unique substrings

• Return the set as an array of strings
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Q2. 
Cycle Detection in a Singly Linked List
Determine if a given singly linked list of integers forms a cycle or not.
A cycle in a linked list occurs when a node's next points back to a previous node in the ...read more
Ans. 
Detect if a singly linked list forms a cycle by checking if a node's next points back to a previous node.
• Traverse the linked list using two pointers, one moving one step at a time and the other moving two steps at a time.

• If the two pointers meet at any point, there is a cycle in the linked list.

• If one of the pointers reaches the end of the list (null), there is no cycle.
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Round duration - 30 minutes
Round difficulty - Easy

This was supposed to be the HR round but out of surprise the interviewer started by giving me a question to code. 
After I approached this question with the right solution he just asked about my family. After that he said to wait. After half an hour the results were announced. A total of three students were hired and I was amongst one of them.

Q1. 
Balanced Parentheses Combinations
Given an integer N representing the number of pairs of parentheses, find all the possible combinations of balanced parentheses using the given number of pairs.
Explanati...read more
Ans. 
Generate all possible combinations of balanced parentheses for a given number of pairs.
• Use recursion to generate all possible combinations of balanced parentheses.

• Keep track of the number of open and close parentheses used in each combination.

• Return the valid combinations as an array of strings.
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It was 2 coding questions of medium level

Q1. Longest substring with non repeating characters
Ans. 
Find the longest substring in a given string that does not contain any repeating characters.
• Use a sliding window approach to iterate through the string.

• Keep track of the characters seen so far using a set.

• Update the start and end indices of the window to find the longest substring.

• Return the length of the longest substring.
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Q2. Candy problem. There is similar question in geeks for geeks
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Q1. Launch modes on android
Ans. 
Launch modes on Android determine how a new instance of an activity is associated with the current task.
• Standard: Creates a new instance of the activity in the task's stack

• SingleTop: If an instance of the activity already exists at the top of the stack, it will not be recreated

• SingleTask: Activity is always at the root of the task and no other activities can be on top of it

• SingleInstance: Similar to SingleTask, but the
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Questios based on Activity backstacks

There were 2 questions to test our basic coding knowledge.

Q1. Some basic introduction followed by sort 2 arrays into a single array.
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Q1. Applications of various data structures.
Ans. 
Data structures are used in various applications like search algorithms, storage systems, and graph algorithms.
• Search algorithms like binary search use arrays and trees for efficient searching.

• Storage systems use data structures like hash tables and linked lists for organizing and accessing data.

• Graph algorithms like Dijkstra's algorithm use graphs and trees for solving complex problems.
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Q1. Some basic hr questions like tell me about yourself, what do you know about magicbricks,where do you see yourself in 5 years etc
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Q1. JavaScript question
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Q1. Coding questions
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Data structure - rainwater trapping

Q1. OOPs concept, core java, sql
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Q2. Car parking lot problem - system design
Ans. 
Design a car parking lot system
• Determine the size and capacity of the parking lot

• Create a database to store information about available spots and occupied spots

• Develop a system to track the entry and exit of vehicles

• Implement a payment system for parking fees

• Incorporate security measures such as CCTV cameras and security personnel

• Provide a user-friendly interface for customers to locate available spots and make payment
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Q1. Rapid fire questions
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Q2. More java springboot
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