Directi Interview Questions, Process, and Tips

Round: Test
Experience: There were 2 questions. Question 1 had 2 points whereas question 2 had 1 point.
Question 1. There is a compressed string eg. ”ab2c3”, the string has lowercase characters and numbers. We can uncompress the given string as follows: whenever we get a number “n” in the string, the portion of the string before the number will repeat “n” times. So in the above example, we get a 2, so string will become “ababc3”, now we get a 3, so final string will be “ababcababcababc”.
Given a compressed string and a number k, you have to output the k’th character in the uncompressed string.1 <= length of string <= 1500
1 <= n <= 1000
1 <= k < 2^31
example:
input: ab2c3 10
output: c
Question 2. There is a string whose characters can only be either ‘a’, ‘b’ or ‘_’ (there can be only one ‘_’ in the string). At each step, we can modify the string as follows:
1. ‘_’ can be swapped with its adjacent character, example “a_ba” can be changed to either “_aba” or “ab_a”.
2. Two characters adjacent to ‘_’ (both on the same side of ‘_’) can be reversed along with the ‘_’ if both characters are different, example, “aa_ba” can be changed to “aaab_” but not to “_aaba” because both characters are ‘a’.
You are given two strings, the initial state and the final state (lengths will be same), you have to output the minimum number of steps required to change the string in initial state to the string in the final state.
example:
input: a_b ab_
output: 1
input: abaa_a b_aaaa
output: 4
reason for example 2:- abaa_a -> aba_aa -> ab_aaa -> _baaaa -> b_aaaa
Hint: Use Breadth first searchThey shortlisted 12 students after this contest for the next round.
Total Questions: 02

Round: Technical Interview
Experience: Question 1. Suppose you are given a string of length n and a set of pairs(i, j such that 0 <= i < j < n). Pair “i, j” (0 based indexing) means that you can swap the i’th and j’th character in the string any number of times. You have to output the lexicographically smallest string that can be produced by doing any number of swaps on the input string.
example:input: zcxfbe
0, 1 0, 2 3, 5
output: cxzebfHint: Try to model the problem to a graph problem.
Question 2. Suppose there are two piles of plates in the table. One has ‘m’ RED plates and other has ‘n’ BLACK plates. In his/her chance, a player can either pick any number of red plates or any number black plates or equal number of red and black plates. A player loses if he cannot make a move in his/her chance. You are playing this game with your friend. Given that you begin the game and both the players play optimally, output ‘L’ if you will lose or ‘W’ if you will win.
example:
input: m = 1, n = 2
output: L
input: m = 2, n = 2
output: W
After this round, they selected 4 people for the next round of interview.

General Tips: Tips:1. There main focus was on string and graph&#44; prepare well for them.2. Practice your codes on paper or google doc, you will not get any editor for coding.3. Keep your concepts clear on all the topics, they can ask you about any minute detail of any data structure or algorithm.
College Name: NA

Round: Test
Experience: General Aptitude + technical questions (C, OOP, DBMS)Aptitude questions (with a few exceptions)were easy, technical questions were of moderate difficulty. C questions like recursive functions, finding output of some code etc.,15 x 1 mark, 10 x 3 marks and 3 x 10 marks questions and 1mark=1min1 mark questions were very simple…For 3 marks questions little bit thinking is necessary but easy ones… like matching kind of questionso 10 marks questions contains puzzles for e.g.: bulbs on/off, probability based questions Eg 1) Given a binary tree, such that each node contains a number. Find the maximum possible sum in going from one leaf node to another. 2) Suppose you have some guests arriving at a party. For each guest, you are given the arrival and departure time. When a guest arrives he is given a wine glass and when he leaves he returns that wine glass (it becomes available to be given to another guest). Find the minimum number of wine glasses needed to serve all the guests. The arrival and departure team can only be between 1800 to 2359 hours.

Round: Technical Interview
Experience: Round 1 Technical ::• The first round was algos round• Panel consisted of one interviewer• He asked me to tell him about myself• Then, he asked if I had passion for something. I talked about web development and we had a very long discussion on many web

technologies, protocols, interoperability, vendor locking, cloud storage, cloud computing, web OSes, domains, DNS, server technologies, web databases. This is where I scored huge points in my interview.• Then he asked very simple questions on merging two sorted arrays, finding the kth element in two sorted arrays, permutations of merging two series such that their relative order is maintainedEg ::1) Suppose you have strings like A, B…, Z, AA, AB, ….AZ and so on. This is similar to the way the columns of excel are named. Given a number you have to find the corresponding string. (e.g. 27 would map to AA). I had to give the algorithm and write the pseudo code for this.2) Given n biased coins, with each coin giving heads with probability Pi, find the probability that on tossing the n coins I will obtain exactly k heads. I had to write the formula for this (i.e. the expression that would give us P (n, k)).3) Given n positive real numbers, find whether there exists a triplet among this set such that, the sum of the triplet is in the range (1, 2). Do it in linear time and O (1) space..

Round: Technical Interview
Experience: Roound 3 Technical Interview • This was my longest (105 minutes) and toughest interview yet.• Q1: Given an array AA = { 4 0 0 3 6 5 4 7 1 0 1 2 }

You start at the first element. From here, you can jump as many places ahead as the value of the cell you are at. E.g. from the initial 4, you can jump to 0, 0, 3 and 6. You are stuck if you end up at a 0. Give an efficient algorithm to find the path with minimum jumps from start of the array to the end. (Note: the most obvious solutions are not the best ones)

• + is string concatenation operator

a1 = “()”

a2 = “(“ + a1 + “)”

a3 = “(“ + a1 + a2 + “)”

a4 = “(“ + a1 + a2 + a3 + “)”

.

.

an = “(“ + a1 + a2 + a3 + …….. + an-1 + “)”

Given n and p, find which bracket would come at pth position in an.• He asked how much programming experience I had, what all programming languages I knew, if I had studied DBMS. Then he asked me questions on javascript, PHP, mySQL.• Then there were questions on OS (like multithreading) and networks (OSI model, TCP/IP model, DNS functioning, IMAP, POP

protocols, encryption etc)• Questions on data structures (difference between trees and hash tables), their applications.Eg :::The length and breadth of my knowledge regarding Databases, networks and data structures was tested. Some of the questions asked were:What are relationships? How are they represented in a database?

What is indexing? Explain it with an example.

What is a hash table?

What is an IP address?

What is a MAC address?

If a MAC address exists why do we need an IP address?

Give the use cases of binary tree?

What is the advantage of an M-ary tree over binary tree?

Given the different prices of a stock over a time period, find the maximum profit that a person can make by buying and selling the stock within the given time period. The number of such entries can run into millions, so time complexity is important. E.g. the prices are 70, 60,100,150,110. The maximum possible profit in this case is (150-60=90).Special Part ::This was the end of the telephonic interview. Probably he was in two minds after this because I was called again after 10 minutes, and two quick questions were asked:How can I contribute to Directi?

What exactly did I do in my internship and how did I benefit my team?

Why I chose ECE if I was so much interested in computer science.

In the end, he gave feedback of how did in the interview and told that I’ll be informed of result later by the HR.But i think The response to these two questions sealed the deal and I was ‘hired’ by Directi .
Tips: Students spend majority of their time doing problems related to data structures and algorithms. However most of students ignore the other core CS subjects. You MUST devote equal time to these subjects, because almost all companies require you to possess a solid understanding of the basic fundamentals of Operating Systems, Databases, Networks, Classes (depending on the profile they are hiring you for).. The way you express yourself is really important. If you are unable to express yourself clearly or lack enthusiasm organizations would see that as a potential red flag. If you are weak in English, practice speaking in front of a mirror (believe me, it helps) or still better give mock interviews to your friends Think out aloud. Whatever idea comes to your mind, share it with the interviewer. Always start by giving a brute force solution to the problem (it helps the interviewer know that you have understood the problem).. Don’t give up on a problem until the last moment. Keep on discussing things with the interviewer; he will give you hints if you are on the right path. CSE guyz might be asked networks, DBMS also.Good problem solving/analytical skills are required.Most of all, passion/zeal for something (like web development in my case) is looked for in applicants.Candidates are expected to know a little bit of everything, but superficial knowledge won’t work.Some experience of working with websites/web apps will be a huge plus.

College Name: BITS PILANI