Hiver Software Developer Intern Interview Questions and Answers

Round duration - 50 minutes
Round difficulty - Easy

This was a Data Structural round.

Q1. 
Distinct Islands Problem Statement
Given a two-dimensional array/list consisting of integers 0s and 1s, where 1 represents land and 0 represents water, determine the number of distinct islands. A group of...read more
Ans. 
Count the number of distinct islands in a 2D array of 0s and 1s.
• Identify islands by performing depth-first search (DFS) on the grid

• Use a set to store the shape of each island and check for duplicates

• Consider translations to determine distinct islands
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Round duration - 50 minutes
Round difficulty - Easy

This was a Data Structural round.

Q1. 
Word Wrap Problem Statement
You are tasked with arranging 'N' words of varying lengths such that each line contains at most 'M' characters, with each word separated by a space. The challenge is to minimiz...read more
Ans. 
The goal is to minimize the total cost of arranging 'N' words on each line with a maximum character limit 'M'.
• Calculate the cost of each line as the cube of extra space characters needed to reach 'M'.

• Minimize the total cost by arranging words to fit within the character limit on each line.

• Ensure each word appears fully on one line without breaking across lines.
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Round duration - 60 minutes
Round difficulty - Easy

This was a System Design round.

Q1. Can you design a system similar to Red Bus that can handle bookings and onboard both vendors and customers to the platform?
Ans. 
Design a system similar to Red Bus for handling bookings and onboarding vendors and customers.
• Implement a user-friendly interface for customers to search and book tickets

• Create a vendor portal for vendors to manage their offerings and availability

• Include payment gateway integration for secure transactions

• Develop a robust backend system for managing bookings, cancellations, and refunds

• Utilize a database to store user in...read more
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Round duration - 50 minutes
Round difficulty - Easy

This was a System Design round

Round duration - 50 minutes
Round difficulty - Easy

This was an HR round.

Round duration - 75 minutes
Round difficulty - Hard

This round was scheduled in the evening hours and all the participants were required to fill a form which was shared 2 days prior to the test date. This form was filled out probably for the security reasons and to ensure that no one disinterested participant gives the test.

Q1. 
Validate BST Problem Statement
Given a binary tree with N nodes, determine whether the tree is a Binary Search Tree (BST). If it is a BST, return true; otherwise, return false.
A binary search tree (BST)...read more
Ans. 
Validate if a given binary tree is a Binary Search Tree (BST) or not.
• Check if the left subtree of a node contains only nodes with data less than the node's data.

• Check if the right subtree of a node contains only nodes with data greater than the node's data.

• Ensure that both the left and right subtrees are also binary search trees.
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Q2. 
Longest Palindromic Subsequence Problem Statement
Given a string A consisting of lowercase English letters, determine the length of the longest palindromic subsequence within A.
Explanation:
• A subsequ...read more
Ans. 
Find the length of the longest palindromic subsequence in a given string.
• Use dynamic programming to solve this problem efficiently.

• Create a 2D array to store the lengths of palindromic subsequences for different substrings.

• Fill the array diagonally based on the characters in the string.

• Return the length of the longest palindromic subsequence for each test case.
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Round duration - 45 minutes
Round difficulty - Medium

There was only one female interviewer for this round. She continuously interacted with me and was giving me some good situational problems that were not very easy to answer. Basically those were open-minded questions which can be answered both ways and that's why I found it quiet hard as per my nature but at the end things went well for me.

Round duration - 120 Minutes
Round difficulty - Easy

Total 3 coding questions were there, out of which I don't remember the last one.

Q1. 
Ninja's Dance Competition Pairing Problem
Ninja is organizing a dance competition and wants to pair participants using a unique method. Each participant chooses a number upon entry, and Ninja selects a nu...read more
Ans. 
Find the number of distinct pairs of participants with a given difference in their chosen numbers.
• Iterate through the list of numbers and check for pairs with the required difference 'K'.

• Use a hash set to keep track of unique pairs to avoid counting duplicates.

• Return the size of the hash set as the number of distinct pairs.
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Q2. 
Longest Common Prefix After Rotation
You are given two strings 'A' and 'B'. While string 'A' is constant, you may apply any number of left shift operations to string 'B'.
Explanation:
Your task is to calcu...read more
Ans. 
Calculate minimum left shift operations to achieve longest common prefix between two strings.
• Apply left shift operations to string B to find longest common prefix with string A

• Count number of shifts needed to achieve longest common prefix

• Handle circular rotation of characters in string B

• Return minimum number of left shift operations for each test case
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Round duration - 60 Minutes
Round difficulty - Easy

Q1. 
Rotate Matrix by 90 Degrees Problem Statement
Given a square matrix 'MATRIX' of non-negative integers, rotate the matrix by 90 degrees in an anti-clockwise direction using only constant extra space.
Inpu...read more
Ans. 
Rotate a square matrix by 90 degrees in an anti-clockwise direction using constant extra space.
• Iterate through each layer of the matrix from outer to inner layers

• Swap elements in groups of 4 to rotate the matrix

• Handle odd-sized matrices separately by adjusting the loop boundaries
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Q2. 
Problem: Sort an Array of 0s, 1s, and 2s
Given an array/list ARR consisting of integers where each element is either 0, 1, or 2, your task is to sort this array in increasing order.
Input:
The input sta...read more
Ans. 
Sort an array of 0s, 1s, and 2s in increasing order.
• Use a three-pointer approach to partition the array into sections for 0s, 1s, and 2s.

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

• After sorting, the array will have 0s at the beginning, followed by 1s, and then 2s.
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Round duration - 60 Minutes
Round difficulty - Easy

This was HR + Technical round
He started with questions on projects and Os and Dbms and Oops
Then asked one coding question

Q1. 
Number of Islands Problem Statement
You are given a non-empty grid that consists of only 0s and 1s. Your task is to determine the number of islands in this grid.
An island is defined as a group of 1s (re...read more
Ans. 
The task is to determine the number of islands in a grid of 0s and 1s connected horizontally, vertically, or diagonally.
• Iterate through the grid and perform depth-first search (DFS) to find connected 1s forming islands

• Mark visited cells to avoid counting the same island multiple times

• Count the number of islands found during DFS traversal
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Round duration - 1 hour
Round difficulty - Medium

Q1. 
First Missing Positive Problem Statement
You are provided with an integer array ARR of length 'N'. Your objective is to determine the first missing positive integer using linear time and constant space. T...read more
Ans. 
Find the smallest positive integer missing from an array of integers.
• Iterate through the array and mark positive integers as visited by changing the sign of the corresponding index.

• After marking all positive integers, iterate again to find the first positive integer with a positive value.

• Return the index of the first positive integer found plus one as the answer.
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Arrays, Graphs majorly asked
Practice Leetcode

Round duration - 45 Minutes
Round difficulty - Easy

Had some small chit-chat regarding how Work from Home is going on for him and me. Later he introduced himself and asked the same.
Coming to technical questions, he asked me the algorithm and also asked me to code the questions mentioned below. Discussed the time complexities and edge cases.

Q1. 
Spiral Matrix Problem Statement
You are given a N x M matrix of integers. Your task is to return the spiral path of the matrix elements.
Input
The first line contains an integer 'T' which denotes the nu...read more
Ans. 
The task is to return the spiral path of elements in a given matrix.
• Iterate over the matrix in a spiral path by keeping track of the boundaries.

• Print the elements in the spiral path as you traverse the matrix.

• Handle cases where the matrix is not a square matrix separately.
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Q2. 
Group Anagrams Problem Statement
Given an array or list of strings called inputStr, your task is to return the strings grouped as anagrams. Each group should contain strings that are anagrams of one anoth...read more
Ans. 
Group anagrams in an array of strings based on character frequency.
• Create a hashmap to store sorted strings as keys and corresponding anagrams as values.

• Iterate through the input strings, sort each string, and add it to the hashmap.

• Return the values of the hashmap as grouped anagrams.
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Round duration - 45 Minutes
Round difficulty - Medium

This round started without any introduction, and he directly jumped into the question. Asked me about the algorithm, and later coded it and ran it. And then he asked me to optimize it. Finally, he asked me if I had any questions.

Q1. 
Tic-Tac-Toe Design Problem
Design a 2-player Tic-Tac-Toe game played on an N * N grid where Player 1 uses ‘X’ and Player 2 uses ‘O’. A move is always valid and occupies an empty spot.
If a player places ...read more
Ans. 
Design a 2-player Tic-Tac-Toe game on an N x N grid where players take turns placing their marks, and the first player to get N marks in a row wins.
• Implement a function move(row, col, player) to handle each player's move and check for a win condition.

• Keep track of the board state and update it after each move.

• Check for winning conditions horizontally, vertically, and diagonally after each move.

• Return the result (0 for ...read more
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Round duration - 60 minutes
Round difficulty - Medium

Timing-> EVENING(5 TO 6)
The interviewer was very sweet and calm.

Q1. 
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 pointer points back to a previous node.
• Use Floyd's Cycle Detection Algorithm to determine if there is a cycle in the linked list.

• Maintain two pointers, one moving at twice the speed of the other.

• If the two pointers meet at any point, there is a cycle in the linked list.
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Q2. 
Boundary Traversal of a Binary Tree
Given a binary tree of integers, your task is to return the boundary nodes of the tree in Anti-Clockwise direction starting from the root node.
Input:
The first line ...read more
Ans. 
Return the boundary nodes of a binary tree in Anti-Clockwise direction starting from the root node.
• Traverse the left boundary nodes in a top-down manner

• Traverse the leaf nodes in a left-right manner

• Traverse the right boundary nodes in a bottom-up manner

• Avoid duplicates in boundary nodes
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Round duration - 60 Minutes
Round difficulty - Easy

It was an online technical interview focusing on DS and algorithms. They asked two questions in this round. He also asked me to code both the questions. I solved both questions with confidence.
They also gave a puzzle to solve. Out of 32 they selected 22 students along with me.

Q1. 
Spiral Matrix Problem Statement
You are given a N x M matrix of integers. Your task is to return the spiral path of the matrix elements.
Input
The first line contains an integer 'T' which denotes the nu...read more
Ans. 
The task is to return the spiral path of elements in a given matrix.
• Iterate through the matrix in a spiral path by adjusting the boundaries of rows and columns.

• Keep track of the direction of traversal (right, down, left, up) to cover all elements.

• Print the elements in the spiral path as you traverse the matrix.

• Handle edge cases like when the matrix is a single row or column.
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Q2. You are given a certain number of eggs and a building with a number of floors. The goal is to find the highest floor from which you can drop an egg without breaking it. What is the optimal strategy to mini...read more
Ans. 
Optimal strategy to minimize number of drops to find highest floor an egg can be dropped without breaking.
• Start by dropping the first egg from a lower floor and incrementally increase the floor until it breaks.

• Once the first egg breaks, use the second egg to perform a binary search between the last successful drop and the floor below the breaking point.

• This strategy ensures the minimum number of drops required to find ...read more
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