Infosys private limited interview experience Real time questions & tips from candidates to crack your interview

Specialist Programmer

Infosys private limited

2 rounds | 2 Coding problems

Siddhartha Goel

Fresher | Apr 2020

Selected

Interview preparation journey

Preparation

Duration: 3 months

Topics: Data Structures, OOPS, Algorithms, DBMS, Networking

Tip

Tip 1 : Practice a lot by doing a lot of DS/Algo Questions
Tip 2 : Do cover DBMS and common SQL Queries for Interview
Tip 3 : Improve upon your time management for exam
Tip 4 : Have some good working projects in your resume

Application process

Where: Other

Eligibility: No criteria

Resume tip

Tip 1 : Have some good working projects in your resume
Tip 2 : Keep your resume clean and simple
Tip 3 : Do categorize your skills like Basic, Intermediate and Expert.

Interview rounds

Round

Easy

Online Coding Interview

Duration60 minutes

Interview date20 Apr 2020

Coding problem1

This round was in evening in Online Proctored Environment. This round consisted of 3 DSA question, with increasing difficulty level.

1. Largest rectangle in a histogram

Hard

25m average time

75% success

0/120

Asked in companies

You have been given an array/list 'HEIGHTS' of length ‘N. 'HEIGHTS' represents the histogram and each element of 'HEIGHTS' represents the height of the histogram bar. Consider that the width of each histogram is 1.

You are supposed to return the area of the largest rectangle possible in the given histogram.

For example :

In the below histogram where array/list elements are {2, 1, 5, 6, 2, 3}.

The area of largest rectangle possible in the given histogram is 10.

Problem approach

1) Begin by making an empty stack.
2) Begin with the first bar and repeat for each subsequent bar 'hist[i]', where I ranges from 0 to n-1.
a) Push I to stack if the stack is empty or hist[i] is higher than the bar at the top of the stack.
b) If this bar is smaller than the top of the stack, keep removing the top of the stack while it is larger. Let hist[tp] be the deleted bar. Calculate the rectangle's area using hist[tp] as the smallest bar. The 'left index' in hist[tp] is the prior (previous to tp) item on the stack, while the 'right index' is I (current index).
3) If the stack is not empty, remove all bars from the stack one by one and go to step 2.b. for every removed bar.

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Round

Medium

Face to Face

Duration45 minutes

Interview date10 Jul 2021

Coding problem1

Online Technical Interview Round. Interviewer was very nice and supportive. Asked good intriguing questions on DSA and DBMS.

1. Find Duplicates In Array

Easy

15m average time

90% success

0/40

Asked in companies

You are given an array/list 'ARR' consisting of N integers, which contains elements only in the range 0 to N - 1. Some of the elements may be repeated in 'ARR'. Your task is to find all such duplicate elements.

Note:

1. All the elements are in the range 0 to N - 1.
2. The elements may not be in sorted order.
3. You can return the duplicate elements in any order.
4. If there are no duplicates present then return an empty array.

Problem approach

The goal is to solve this in O(n) time on average using Hashing. A hash table is used to keep track of elements and their numbers. After storing the counts, we traverse the input array again and print the elements with multiple counts. We set count to 0 after printing each output element to ensure that it is printed just once.

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