HackerRank interview experience Real time questions & tips from candidates to crack your interview

Technical Consulting Engineer

HackerRank

2 rounds | 4 Coding problems

vidya gupta

Fresher | May 2021

Rejected

Interview preparation journey

Preparation

Duration: 5 months

Topics: OOPS, System Design, Algorithms, Data Structures, DBMS

Tip

Tip 1 : Prepare System Design
Tip 2 : Practice DSA Questions properly
Tip 3 : Practice OOPS and DBMS Concepts

Application process

Where: Referral

Eligibility: No criteria

Resume tip

Tip 1 : Your Resume should consist mainly of skills, projects, and achievements. Projects would play a crucial part in your interview and you should have at least one most relevant and good project that shows how strong your concepts are in development.
Tip 2 : The most important tip is that never lie on your resume If you have worked upon some technology for the project part only and don't know the proper depth you could write basics only in your resume.

Interview rounds

Round

Easy

Online Coding Test

Duration90 minutes

Interview date5 May 2021

Coding problem3

This round had 3 coding question ranging from easy - medium difficulty so was able to complete them pretty quickly.

1. Single Element in a Sorted Array

Easy

15m average time

85% success

0/40

Asked in companies

You are given a sorted array ‘arr’ of ‘n’ numbers such that every number occurred twice in the array except one, which appears only once.

Return the number that appears once.

Example:

Input: 'arr' = [1,1,2,2,4,5,5]

Output: 4 

Explanation: 
Number 4 only appears once the array.

Note :

Exactly one number in the array 'arr' appears once.

Problem approach

Take the first number, then find its last occurrence or upper bound using binary search.
Then count it as one unique element.
Place pointer to next different element and repeat the same step.

Try solving now

2. Wildcard Pattern Matching

Hard

50m average time

30% success

0/120

Asked in companies

Given a text and a wildcard pattern of size N and M respectively, implement a wildcard pattern matching algorithm that finds if the wildcard pattern is matched with the text. The matching should cover the entire text not partial text.

The wildcard pattern can include the characters ‘?’ and ‘*’

 ‘?’ – matches any single character 
 ‘*’ – Matches any sequence of characters(sequence can be of length 0 or more)

Problem approach

Case 1: The character is ‘*’ . Here two cases arises as follows:

We can ignore ‘*’ character and move to next character in the Pattern.
‘*’ character matches with one or more characters in Text. Here we will move to next character in the string.
Case 2: The character is ‘?’
We can ignore current character in Text and move to next character in the Pattern and Text.

Case 3: The character is not a wildcard character
If current character in Text matches with current character in Pattern, we move to next character in the Pattern and Text. If they do not match, wildcard pattern and Text do not match.

Try solving now

3. Remove String

Moderate

35m average time

60% success

0/80

Asked in companies

You have been given a linked list where each node has a single character. You have also been given a string 'STR'.

You have to remove all the occurrences of string STR from the linked list.

Note:

1. Start checking from the end of the linked list and not from the beginning. For example, if the linked list is ( a, b, a ,b, a)  and the string is equal to “aba” , then the answer should be (a b), not (b a).

2. After removing an occurrence check again for new formations.

Problem approach

We make a copy of our string s (x in code) and then iterate over the string s.
Now in the current iteration if j is greater than or equal to m that means that we have seen at least m elements, so we can check whether the substring of last m characters is equal to part or not. If it is equal, we reduce the variable 'j' by m showing that we have removed this substring and now we will overwrite the characters from index j.
Finally we will return the substring of x of length j.

Try solving now

Round

Medium

Video Call

Duration60 minutes

Interview date2 Jun 2021

Coding problem1

This round was take by a senior engineer who asked a lot of questions on resume, oops, tech stack used, why a particular thing is used in project, what could be alternatives to that and one system design question as well.

1. System Design

Design a URL Shortener

Problem approach

Tip 1 : Prepare for these questions as well as generally they not asked for intern position but you never know.
Tip 2 : Explain the approach before moving to solution.
Tip 3 : Keep the interviewer engaged.