Infrrd UI Developer Interview Questions and Answers

Medium level coding questions on hackerrank ,1:30hr, topic- Array , DP , Matrix , Binary Search

Q1. Was Asked to Implement Hashmap and Question on OOPS and Dbms , SQL and Indexing
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Q1. Brief Introduction
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Q2. Rotten Oranges and basics of bfs and DFS
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Round duration - 90 minutes
Round difficulty - Medium

Timing was 10AM. The platform was quite good.

Q1. Maximum size rectangle sub-matrix with all 1's
You are given an 'N' * 'M' sized binary-valued matrix 'MAT, where 'N' is the number of rows and 'M' is the number of colum...read more
Ans. Dynamic Programming.
1. We start from the first row and move downwards.
2. We create three 1-dimensional arrays HEIGHT[], LEFT[], RIGHT[].
3. ‘HEIGHT’[i]: stores the number of current continuous 1’s in column i.
4. LEFT[i] : stores the leftmost index ‘j’ such that all indices say ‘K’, ‘K’ belongs to [j, i], ‘HEIGHT’[k] >= ‘HEIGHT’[i].
5. RIGHT [i]: stores the rightmost index ‘j’ such that all indices say ‘K’, ‘K’ belongs to [i, j], ‘HE...read more
Answered by CodingNinjas
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Q2. Binary Tree Maximum Path Sum
You are given a binary tree with ‘N’ nodes.
Your task is to find the “Maximum Path Sum” for any path.
Note :
1. A ‘path’ is a sequence of adjacent pair nodes with an edge ...read more
Ans. Recursive Approach
The idea here is to use the recursion. For each node, We can calculate the maximum path sum by keeping track of the following paths:
• Max path sum starting from Left child + Max Path sum starting from Right child + Node’s value.
• Max path sum starting from Left child + Node’s value
• Max path sum starting from Right child + Node’s value
• Node’s value
 
We then pick the maximum one among them. The root of ev...read more
Answered by CodingNinjas
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Q3. Minimum number of swaps required to sort an array
You have been given an array 'ARR' of 'N' distinct elements.
Your task is to find the minimum no. of swaps required to sort the array.
F...read more
Ans. Naive Approach
While iterating over the array, check the current element, and if not in the correct place, replace that element with the index of the element which should have come in this place.
 
Below is the algorithm:
1. Create a copy of the given input array and store it in temp.
2. Sort the temp array.
3. Iterate over the input array, and check whether the current element is at the right place or not by comparing it with t...read more
Answered by CodingNinjas
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Q4. Infix to Postfix
You are given a string EXP which is a valid infix expression. Convert the given infix expression to postfix expression.
Infix expression is of the form a op b. Where operator is is betw...read more
Ans. Stack
We will scan the expression from left to write and if we encounter an operand we will append it to our answer. If we encounter an operator we will pop all the operators with equal or higher precedence and append them to our answer. And push the current operator. In the end, we will empty the stack.
Order of precedence = [ ‘^’, ‘*’ and ‘/’, ‘+’ and ‘-’, ‘(’, ‘)’]
Order of precedence [ link ]
The algorithm will be-
1. ANS ...read more
Answered by CodingNinjas
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Round duration - 90 minutes
Round difficulty - Medium

They share doc file link which consist of 5 programming questions

Q1. Reverse Words in a String
You are given a string of length N. You need to reverse the string word by word. There can be multiple spaces between two words and there can be leading or trailing spaces but in ...read more
Ans. Brute force
• Create a String ans to store the reversed string.
• Initialize a variable i to 0 and iterate the whole string through a while loop.
• Skip initial spaces by just incrementing i.
• Create a String that will store the current word.
• Add the currentword and space at the beginning of ans.
• After traversing the whole string, check if the length of ans is greater than 0 then return ans after removing the last space otherwise r...read more
Answered by CodingNinjas
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Q2. Fibonacci Member
Given a number N, figure out if it is a member of fibonacci series or not. Return true if the number is member of fibonacci series else false.
Fibonacci Series is defined by the recurren...read more
Ans. Space Complexity: Explanation: Time Complexity: Explanation:
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Q3. Maximum Difference
You are given an array 'ARR' of the 'N' element. Your task is to find the maximum difference between any of the two elements from 'ARR'.
If the maximum differen...read more
Ans. Find Max And Min
We will iterate over ARR and find the MAX and MIN of the ARR. And if the MAX - MIN is odd the return “ODD” else return "EVEN". 
The algorithm will be-
1. MAX = -1, MIN= 10 ^ 9 + 1
2. For VAL in ARR.
   1. If MAX < VAL
      1. MAX = VAL
   2. If MIN > VAL
      1. MIN = VAL
3. IF (MAX-MIN) % 2
   1. Return ODD
4. ELSE
   1. Return EVEN
Space Complexity: O(1)Explanation:
O(1).
 
Since constant space is used.
Time Complexity: O(n)Explanation:
O(N), where N ...read more
Answered by CodingNinjas
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Q4. Remainder when divided by 11
You are given a number N. You need to find the remainder when N is divided by 11.
Note :
Number N may be very large.
Input format :
The first line contains an integer '...read more
Ans. Using Modulo Property
1. Since the number is very large we can not simply calculate N % 11.
2. Now, any number say 256 % 11 can be calculated as (25*10 + 6)%11. Which in turn can be calculated as (( 25*10)%11+ 6)%11 or ( (25%11)*10 + 6)%11. Similarly 25%11 can be calculated as (2*10+5)%11. Therefore , 256 %11 can be finally calculated as ( ( (2*10 + 5)%11 )*10 + 6)%11.
3. So, the idea is to store the number N in string Str.
4. Take a ...read more
Answered by CodingNinjas
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Round duration - 60 minutes
Round difficulty - Medium

In this round interviewer asked me to solve 3 programming questions.

Q1. Selection Sort
Selection sort is one of the sorting algorithms that works by repeatedly finding the minimum element from the unsorted part of the array and putting it at the beginning of the unsorted regio...read more
Ans. Selection Sort Approach
Selection sort is a standard sorting algorithm that uses nested loops to find all the minimum elements in the array in each iteration and swap them with the starting element of the unsorted region of the array.
 
Steps :
• Use a minValue variable to find the index of the minimum element of the array.
• Use a loop to iterate over all the elements of the array.
• Use a nested loop to find the minimum ele...read more
Answered by CodingNinjas
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Q2. String Palindrome
Given a string, determine if it is a palindrome, considering only alphanumeric characters.
Palindrome
A palindrome is a word, number, phrase, or other sequences of characters which read...read more
Ans. Space Complexity: Explanation: Time Complexity: Explanation:
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Q3. Star Pattern
Print the following pattern
Pattern for N = 4


The dots represent spaces.



Input Format :
N (Total no. of rows)
Output Format :
Pattern in N lines
Constraints :
0 <= N <=...read more
Ans. Space Complexity: Explanation: Time Complexity: Explanation:
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Round duration - 60 minutes
Round difficulty - Easy

This was the HR round. They asked me simple HR questions and 1 coding question.

Q1. Basic HR Questions
What experience do you have that would be relevant to this role?
What do you know about our company’s product/services?
Ans. 
Tip 1 : Stick to your first answer and that will show the confidence.
Tip 2 : Give genuine answers and be confident.
Answered by CodingNinjas
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Q2. Count characters
Write a program to count and print the total number of characters (lowercase english alphabets only), digits (0 to 9) and white spaces (single space, tab i.e. '\t' and newline i.e....read more
Ans. Space Complexity: O(1)Explanation: Time Complexity: O(1)Explanation:
Answered by CodingNinjas
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Q1. Related to front end technologies like HTML, CSS, JS
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Q1. Basic questions on HTML, CSS, JS Focus on array questions and read methods of array before
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Q1. Managerial round questions based on scenario to check how you think/react on the particular situation
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