Andhra Pradesh Industrial Infrastructure Corporation limited. Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Easy

Resume based and 1 coding question. Briefly discussed about projects in resume and questions were completely related to projects mentioned.

Q1. 
Find Duplicate in Array Problem Statement
You are provided with an array of integers 'ARR' consisting of 'N' elements. Each integer is within the range [1, N-1], and the array contains exactly one duplica...read more
Ans. 
Find the duplicate element in an array of integers.
• Iterate through the array and keep track of seen elements using a set or hashmap.

• If an element is already in the set, it is the duplicate element.

• Return the duplicate element once found.
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Round duration - 60 minutes
Round difficulty - Medium

This round was completely pen and paper coding round. 3 coding questions were asked.

Q1. 
Sum Root to Leaf Numbers
You are given an arbitrary binary tree consisting of N nodes, each associated with an integer value from 1 to 9. Each root-to-leaf path can be considered a number formed by concat...read more
Ans. 
Calculate the total sum of all root to leaf paths in an arbitrary binary tree.
• Traverse the tree from root to leaf nodes, keeping track of the current path sum.

• Add the current node value to the path sum and multiply by 10 for each level.

• When reaching a leaf node, add the final path sum to the total sum.

• Return the total sum modulo (10^9 + 7) as the final result.
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Q2. 
Subarray Challenge: Largest Equal 0s and 1s
Determine the length of the largest subarray within a given array of 0s and 1s, such that the subarray contains an equal number of 0s and 1s.
Input:
Input beg...read more
Ans. 
Find the length of the largest subarray with equal number of 0s and 1s in a given array.
• Iterate through the array and maintain a count of 0s and 1s encountered so far.

• Store the count difference in a hashmap with the index as key.

• If the same count difference is encountered again, the subarray between the two indices has equal 0s and 1s.
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Q3. 
The Skyline Problem
Compute the skyline of given rectangular buildings in a 2D city, eliminating hidden lines and forming the outer contour of the silhouette when viewed from a distance. Each building is ...read more
Ans. 
Compute the skyline of given rectangular buildings in a 2D city, eliminating hidden lines and forming the outer contour of the silhouette.
• Iterate through the buildings and create a list of critical points (x, y) where the height changes.

• Sort the critical points based on x-coordinate and process them to form the skyline.

• Merge consecutive horizontal segments of equal height into one to ensure no duplicates.

• Return the fin...read more
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Round duration - 20 minutes
Round difficulty - Easy

Only one coding question was asked with time limit of 10 minutes

Q1. 
Word Break Problem Statement
You are provided with a continuous non-empty string (referred to as 'sentence') which contains no spaces and a dictionary comprising a list of non-empty strings (known as 'wor...read more
Ans. 
Given a dictionary of words and a continuous string, generate all possible sentences by inserting spaces.
• Iterate through the continuous string and check all possible substrings to see if they are in the dictionary.

• Use recursion to generate all possible sentences by inserting spaces at different positions.

• Return the valid sentences formed using the words from the dictionary.
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Round duration - 60 minutes
Round difficulty - Easy

This was a technical round with questions on CSS and Node js.
Tip : Have a basic knowledge about : SASS,Susy,Jade,npm,grunt,gulp,yeoman,LibSASS

Q1. What are the different attributes of the CSS position property?
Ans. 
The CSS position property defines the positioning method of an element.
• Static: Default position, elements are positioned according to the normal flow of the document.

• Relative: Positioned relative to its normal position.

• Absolute: Positioned relative to the nearest positioned ancestor.

• Fixed: Positioned relative to the viewport, does not move when the page is scrolled.

• Sticky: Acts like a combination of relative and fixed ...read more
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Q2. What are the data types that SassScript supports?
Ans. 
SassScript supports data types like numbers, strings, colors, booleans, lists, and maps.
• Numbers: Can be integers or decimals, with or without units (e.g. 10, 2.5px)

• Strings: Can be enclosed in single or double quotes (e.g. 'Hello', "World")

• Colors: Represented in various formats like hex, RGB, or named colors (e.g. #FF0000, rgb(255, 0, 0), red)

• Booleans: Represented as true or false values

• Lists: Ordered collection of valu...read more
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Q3. What are Grunt modules or plugins?
Ans. 
Grunt modules or plugins are extensions that provide additional functionality to the Grunt task runner.
• Grunt modules or plugins are used to automate tasks in web development.

• They can be used for tasks like minification, compilation, unit testing, etc.

• Examples of Grunt plugins include grunt-contrib-uglify for minifying JavaScript files and grunt-sass for compiling Sass files.
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Q4. What is the difference between Sockets and Ajax?
Ans. 
Sockets allow real-time bidirectional communication between client and server, while Ajax enables asynchronous communication for updating parts of a web page without reloading.
• Sockets provide a continuous connection for real-time data exchange, while Ajax makes asynchronous requests to update specific parts of a web page.

• Sockets are commonly used in applications requiring real-time updates like chat applications, onlin...read more
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Round duration - 60 minutes
Round difficulty - Easy

This was a technical round with questions on Java script, Web Fundamentals etc.
Tip : Have knowledge about Closures,Prototypes,Function/variable hoisting,prototypal inheritance,modular pattern,JSONP,this etc

Q1. How does a server work?
Ans. 
A server is a computer or software that provides functionality for other programs or devices, typically over a network.
• A server receives requests from clients and processes them to provide the requested services or data.

• Servers can host websites, store files, manage databases, or perform other specialized tasks.

• Examples of servers include web servers like Apache or Nginx, database servers like MySQL or PostgreSQL, and ...read more
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Q2. What is the difference between a function expression and a function declaration?
Ans. 
Function expression is assigned to a variable, while function declaration is hoisted to the top of the scope.
• Function expression is not hoisted, while function declaration is hoisted.

• Function expression can be anonymous, while function declaration must have a name.

• Function expression can be assigned to a variable, while function declaration cannot.
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Round duration - 30 minutes
Round difficulty - Easy

This was a puzzle round. 2 puzzles were given to solve .

Q1. You have a bag of coins, and you need to determine which coins are of different denominations. What strategy would you use to identify the coins?
Ans. 
Use a combination of weighing and counting to identify coins of different denominations.
• Separate coins by weight to identify different denominations (e.g. pennies, nickels, dimes, quarters)

• Count the number of each denomination to confirm the identification

• Use a scale to measure weight differences between coins
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Q2. The Josephus problem is a theoretical problem related to a certain counting-out game. In this problem, a group of people stands in a circle and every k-th person is eliminated until only one person remains...read more
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Round duration - 60 minutes
Round difficulty - Easy

Technical round with questions based on data structures and algorithms.

Q1. 
Count Inversions Problem Statement
Given an integer array ARR of size N, your task is to find the total number of inversions that exist in the array.
An inversion is defined for a pair of integers in the...read more
Ans. 
Count the total number of inversions in an integer array.
• Iterate through the array and for each pair of indices, check if the conditions for inversion are met.

• Use a nested loop to compare each pair of elements in the array.

• Keep a count of the inversions found and return the total count at the end.
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Q2. 
Add Two Numbers Represented as Linked Lists
Given two linked lists representing two non-negative integers, where the digits are stored in reverse order (i.e., starting from the least significant digit to ...read more
Ans. 
Add two numbers represented as linked lists in reverse order and return the sum as a linked list.
• Traverse both linked lists simultaneously while keeping track of carry.

• Create a new linked list to store the sum digits.

• Handle cases where one list is longer than the other.

• Remember to consider the carry in the last step of addition.
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Q3. 
Connect Nodes at the Same Level
Given a binary tree where each node has at most two children, your task is to connect all adjacent nodes at the same level. You should populate each node's 'next' pointer t...read more
Ans. 
Connect adjacent nodes at the same level in a binary tree by populating each node's 'next' pointer.
• Traverse the tree level by level using a queue.

• For each node, connect it to the next node in the queue.

• If there is no next node, set the 'next' pointer to NULL.
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Round duration - 60 minutes
Round difficulty - Easy

Technical round with questions based on data structures and algorithms.

Q1. 
Word Ladder Problem Statement
Given two strings, BEGIN and END, along with an array of strings DICT, determine the length of the shortest transformation sequence from BEGIN to END. Each transformation inv...read more
Ans. 
The Word Ladder problem involves finding the shortest transformation sequence from one word to another by changing one letter at a time.
• Use breadth-first search to find the shortest transformation sequence.

• Create a graph where each word is a node and edges connect words that differ by one letter.

• Keep track of visited words to avoid cycles and optimize the search process.

• Return -1 if no transformation sequence is possib...read more
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Q2. 
Ninja and Sorted Array Merging Problem
Ninja is tasked with merging two given sorted integer arrays ARR1 and ARR2 of sizes 'M' and 'N', respectively, such that the merged result is a single sorted array w...read more
Ans. 
Merge two sorted arrays into one sorted array within the first array.
• Create a pointer for the end of each array to compare and merge elements.

• Start from the end of the first array and compare elements from both arrays to merge.

• Continue merging elements until all elements from the second array are merged into the first array.
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Q3. 
Count Ways to Reach the N-th Stair Problem Statement
You are provided with a number of stairs, and initially, you are located at the 0th stair. You need to reach the Nth stair, and you can climb one or tw...read more
Ans. 
The problem involves determining the number of distinct ways to climb from the 0th to the Nth stair, with the ability to climb one or two steps at a time.
• Use dynamic programming to solve this problem efficiently.

• Consider the base cases where N=0 and N=1 separately.

• For N>1, the number of ways to reach the Nth stair is the sum of the number of ways to reach the (N-1)th stair and the number of ways to reach the (N-2)th...read more
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Round duration - 60 minutes
Round difficulty - Medium

Technical round with questions based on data structures and algorithms.

Q1. 
Shortest Bridge Problem Statement
Two characters, Tony Stark and Thanos, reside on two separate islands within a 2-D binary matrix of dimensions N x M. Each matrix cell has a value of either 1 (land) or 0...read more
Ans. 
The task is to find the shortest path of transformed 0s that connects two islands in a 2-D binary matrix.
• Identify the two islands in the matrix as distinct connected components of 1s.

• Construct a bridge by converting some 0s to 1s to connect the two islands.

• Output the minimal length of the bridge needed to connect the two islands for each test case.
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Q2. 
Overlapping Intervals Problem Statement
You are given the start and end times of 'N' intervals. Write a function to determine if any two intervals overlap.
Note:
If an interval ends at time T and anothe...read more
Ans. 
Determine if any two intervals overlap based on start and end times.
• Iterate through intervals and check for any overlapping intervals

• Consider edge cases where intervals end and start at the same time

• Return true if any two intervals overlap, otherwise false
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Q3. 
Fixing a Swapped Binary Search Tree
Given a Binary Search Tree (BST) where two nodes have been swapped by mistake, your task is to restore or fix the BST without changing its structure.
Input:
The first...read more
Ans. 
Restore a Binary Search Tree by fixing two swapped nodes without changing its structure.
• Identify the two swapped nodes by performing an inorder traversal of the BST.

• Swap the values of the two identified nodes.

• Perform another inorder traversal to restore the BST structure.

• Ensure no extra space is used other than the recursion stack.
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Round duration - 60 minutes
Round difficulty - Medium

Technical round with questions based on System design and data structures and algorithms.

Q1. How would you implement a Ctrl+F (find) functionality in a file?
Ans. 
Implement Ctrl+F functionality in a file using string search algorithms.
• Read the file content into a string variable

• Implement a string search algorithm like Knuth-Morris-Pratt or Boyer-Moore

• Allow user input for the search query and display the results
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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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Round duration - 60 minutes
Round difficulty - Medium

Technical round with questions based on DSA.

Q1. 
Maximum Level Sum Problem Statement
Given a binary tree with integer nodes, your task is to determine the maximum level sum among all the levels in the binary tree. The sum at any level is the sum of all ...read more
Ans. 
Find the maximum level sum in a binary tree with integer nodes.
• Traverse the binary tree level by level and calculate the sum of nodes at each level.

• Keep track of the maximum level sum encountered so far.

• Return the maximum level sum as the output.
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Q2. 
Maximum Sum Circular Subarray Problem Statement
Find the maximum possible sum of a non-empty subarray from a given circular array/list ARR containing N integers.
Explanation:
The array is circular, mean...read more
Ans. 
Find the maximum sum of a non-empty subarray from a circular array.
• Identify the maximum sum of a non-empty subarray within the circular array

• Consider both normal and circular subarrays to find the maximum sum

• Implement a function to solve the problem efficiently
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Q3. 
Sum of Big Integers Problem Statement
Given two integers, NUM1 and NUM2, as strings, your task is to compute and return the sum of these numbers.
Input:
The first line contains an integer T, the number ...read more
Ans. 
Implement a function to compute the sum of two large integers given as strings.
• Convert the input strings to integers and add them digit by digit from right to left, considering carry over.

• Handle cases where one number is longer than the other by padding with zeros.

• Return the final sum as a string.
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Round duration - 60 minutes
Round difficulty - Easy

Briefly discussed about projects in resume and questions were completely related to projects mentioned. And then he asked questions based on DSA.

Q1. 
Longest Substring Without Repeating Characters Problem Statement
Given a string S of length L, determine the length of the longest substring that contains no repeating characters.
Example:
Input:
"abac...read more
Ans. 
Find the length of the longest substring without repeating characters in a given string.
• Use a sliding window approach to keep track of the longest substring without repeating characters.

• Use a hashmap to store the index of each character in the string.

• Update the start index of the window when a repeating character is encountered.

• Calculate the maximum length of the substring as you iterate through the string.

• Return the m...read more
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Q2. 
Word Break Problem - Generate Sentences
Given a non-empty string sentence containing no spaces and a dictionary of non-empty strings words, your task is to construct and return all possible meaningful sen...read more
Ans. 
Given a string without spaces and a dictionary of words, generate all possible sentences by inserting spaces.
• Use backtracking to generate all possible combinations of words from the dictionary to form sentences

• Iterate through the string and try to match substrings with words from the dictionary

• Recursively build sentences by adding words that match the substrings

• Return all valid sentences formed
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Round duration - 60 minutes
Round difficulty - Easy

Technical round where the interviewer asked me 2 DSA problems.

Q1. 
Replace Spaces in a String
Given a string STR consisting of words separated by spaces, your task is to replace all spaces between words with the characters "@40".
Input:
The first line contains an integ...read more
Ans. 
Replace spaces in a string with '@40'.
• Iterate through the string and replace spaces with '@40'.

• Use string manipulation functions to achieve the desired output.

• Handle multiple test cases by looping through each input string.
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Q2. 
Painter's Partition Problem Statement
Given an array/list representing boards, where each element denotes the length of a board, and a number ‘K’ of available painters, determine the minimum time required...read more
Ans. 
The problem involves determining the minimum time required to paint all boards with a given number of painters.
• Iterate through the array to find the maximum board length.

• Use binary search to find the minimum time required to paint all boards.

• Optimize the painting process by assigning continuous sections of boards to painters.
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