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Application Developer

Oracle
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4 rounds | 12 Coding problems

Interview preparation journey

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Preparation
Duration: 4 Months
Topics: Data Structures, Algorithms, System Design, Aptitude, DBMS, OOPS
Tip
Tip

Tip 1 : Must do Previously asked Interview as well as Online Test Questions.
Tip 2 : Go through all the previous interview experiences from Codestudio and Leetcode.
Tip 3 : Do at-least 2 good projects and you must know every bit of them

Application process
Where: Campus
Eligibility: Above 7 CGPA
Resume Tip
Resume tip

Tip 1 : Have at-least 2 good projects explained in short with all important points covered.
Tip 2 : Every skill must be mentioned.
Tip 3 : Focus on skills, projects and experiences more.

Interview rounds

01
Round
Medium
Online Coding Test
Duration60 Minutes
Interview date9 Oct 2015
Coding problem2

This was a proctured online coding test where we had 2 questions to solve under 60 minutes. Both the questions were of Easy to Medium level of difficulty and can be solved if one has a decent command over Data Structures and Algorithms.

1. Count Subsequences

Moderate
30m average time
60% success
0/80
Asked in companies
OracleDell TechnologiesHCL Technologies

You have been given an integer array/list 'ARR' of size 'N'. Your task is to return the total number of those subsequences of the array in which all the elements are equal.

A subsequence of a given array is an array generated by deleting some elements of the given array with the order of elements in the subsequence remaining the same as the order of elements in the array.

Note :
As this value might be large, print it modulo 10^9 + 7
Problem approach

Approach :
1) Store the frequency of each element in a hashmap (say, ‘FREQ’).

2) Maintain a variable ‘RESULT’ which stores the final answer.

3) For each element present in the hashmap,
3.1) Calculate the value of (2^eleCount - 1) % MOD, ‘eleCount’ is frequency of current element.
3.2) Add the above value to ‘RESULT’

4) The final answer is the value of ‘RESULT’ after we are done iterating over all the elements of the hashmap.

TC : O(N), where N=size of the array
SC : O(N)

Try solving now

2. Anagram Pairs

Moderate
30m average time
60% success
0/80
Asked in companies
AdobeThought WorksHSBC

You are given two strings 'str1' and 'str1'.


You have to tell whether these strings form an anagram pair or not.


The strings form an anagram pair if the letters of one string can be rearranged to form another string.

Pre-requisites:

Anagrams are defined as words or names that can be formed by rearranging the letters of another word. Such as "spar" can be formed by rearranging letters of "rasp". Hence, "spar" and "rasp" are anagrams. 

Other examples include:

'triangle' and 'integral'
'listen' and 'silent'
Note:
Since it is a binary problem, there is no partial marking. Marks will only be awarded if you get all the test cases correct. 
Problem approach

Approach :

1) Sort both strings, so that all the same characters come together
2) Then loop through both strings together and check each element in both strings one by one
3) If at any position, the characters are found to be different or if the lengths of the two strings are different, they cannot be anagrams
4) Otherwise, they will be anagrams.

TC : O(N * log(N) + (M * log(M))), where N and M are the lengths of the two input strings.
SC : O(1)

Try solving now
02
Round
Medium
Face to Face
Duration60 Minutes
Interview date10 Oct 2015
Coding problem4

This round had one preety simple question related to DSA and then I was asked some questions revolving around DBMS and OOPS. I was also asked to write a simple SQL query at the end.

1. Transpose of a Matrix

Easy
15m average time
80% success
0/40
Asked in companies
OracleZSPolicyBazaar.com

You are given a matrix ‘MAT’. Print and return the transpose of the matrix. The transpose of a matrix is obtained by changing rows to columns and columns to rows. In other words, transpose of a matrix A[][] is obtained by changing A[i][j] to A[j][i].

For example:
Let matrix be : 
1 2
3 4

Then transpose of the matrix will be: 
1 3
2 4
Problem approach

Approach :

1) Declare2-dimensional array t to store the transpose of the matrix. This array will have the reversed dimensions as of the original matrix.

2) The next step is to loop through the original array and to convert its rows to the columns of matrix t.
2.1) Declare 2 variables i and j.
2.2) Set both i,j=0
2.3) Repeat until i 2.3.1) Repeat until j 2.3.2) t[i][j] = p[j][i]
2.3.3) j=j+1**
2.4) i=i+1

3) The last step is to display the elements of the transposed matrix t.

TC : O(N*M), where N=number of rows and M=number of columns in the matrix.
SC : O(N*M)

//Pseudo Code :

void transpose(int p[][n], int t[][m])
{
for(int i=0; i for(int j=0; j t[i][j] = p[j][i];

for(int i=0; i {
for(int j=0; j cout< cout< }
}

Try solving now

2. DBMS Question

What is the main difference between UNION and UNION ALL?

Problem approach

UNION and UNION ALL are used to join the data from 2 or more tables but UNION removes duplicate rows and picks the rows which are distinct after combining the data from the tables whereas UNION ALL does not remove the duplicate rows, it just picks all the data from the tables.

3. SQL Question

Given an Employee Table, find the Nth highest salary from it.

Problem approach

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
DECLARE M INT;
SET M=N-1;
RETURN (
SELECT DISTINCT Salary FROM Employee ORDER BY Salary DESC LIMIT M, 1
);
END

4. OOPS Question

What do you mean by virtual functions in C++?

Problem approach

1) A C++ virtual function is a member function in the base class that you redefine in a derived class. It is declared using the virtual keyword.
2) It is used to tell the compiler to perform dynamic linkage or late binding on the function.
3) When the function is made virtual, C++ determines which function is to be invoked at the runtime based on the type of the object pointed by the base class pointer.

Some rules regarding virtual function :

i) Virtual functions must be members of some class.
ii) Virtual functions cannot be static members.
iii) They are accessed through object pointers.
iv) They can be a friend of another class.
v) A virtual function must be defined in the base class, even though it is not used.
vi) We cannot have a virtual constructor, but we can have a virtual destructor

03
Round
Medium
Face to Face
Duration60 Minutes
Interview date10 Oct 2015
Coding problem4

This round had questions from Linked List followed by some questions from OS and then at last I was asked an interesting puzzle.

1. Middle Of Linked List

Easy
20m average time
80% success
0/40
Asked in companies
SamsungGoldman SachsOracle

Given a singly linked list of 'N' nodes. The objective is to determine the middle node of a singly linked list. However, if the list has an even number of nodes, we return the second middle node.

Note:
1. If the list is empty, the function immediately returns None because there is no middle node to find.
2. If the list has only one node, then the only node in the list is trivially the middle node, and the function returns that node.
Problem approach

Approach :
1) If the head is NULL, we simply return HEAD.
2) If there is only one element in the linked list, we simply return it as it is the midpoint.
3) Otherwise, we initialise 2 pointers ‘fast’ and ‘slow’ both poiniting to head initially.
4) We traverse the linked list until fast is the last element or fast is beyond the linked list i.e it points to NULL.
5) In each iteration, the ‘fast’ pointer jumps 2 times faster as compared to ‘slow’ pointer.
6) Finally, once the loop terminates, ‘slow’ pointer will be pointing to the middle element of the linked list, hence we return the ‘slow’ pointer.

TC : O(N), where ‘N’ denotes the number of elements in the given Linked list.
SC : O(1)

Try solving now

2. OS Question

Explain multitasking and multiprogramming.

Problem approach

Multitasking :
1) In Multitasking, a single resource is used to process multiple tasks.
2) The process resides in the same CPU.
3 It is time sharing as the task assigned switches regularly.
4) Multitasking follows the concept of context switching.



Multiprogramming : 
1) In multiprogramming, multiple programs execute at a same time on a single device.
2) The process resides in the main memory.
3) It uses batch OS. The CPU is utilized completely while execution.
4) The processing is slower, as a single job resides in the main memory while execution.

3. OS Question

What is the major difference b/w 32-bit and 64-bit processors?

Problem approach

A major difference between 32-bit processors and 64-bit processors is the number of calculations per second they can perform, which affects the speed at which they can complete tasks. 64-bit processors can come in dual-core, quad-core, six-core, and eight-core versions for home computing. Multiple cores allow for an increased number of calculations per second that can be performed, which can increase the processing power and help make a computer run faster. Software programs that require many calculations to function smoothly can operate faster and more efficiently on the multi-core 64-bit processors, for the most part.

4. Puzzle

There are n glasses on the table, all standing upside down. In one move, you are allowed to turn over exactly n – 1 of them. Determine all values of n for which all the glasses can be turned up in the minimum number of moves.

Problem approach

Approach : 

There exists 2 cases, i.e, when the value of n is odd and when the value of n is even. If the value of n is odd, then there exists no solution.If the value of n is even, the problem can be solved in n moves, which is the minimum number of moves required.

1) If n is odd : As in one move,we are allowed to turn over exactly n – 1 of them.If n is odd then n – 1 i.e, the number of glasses turned over in one move, is even. Therefore, the parity of the number of glasses that are upside down will always remain odd, as it was in the initial position. Hence, the final position in which the number of upside down glasses is 0, which is even, cannot be reached.

2) If n is even : Let us assume that the glasses are numbered from 1 to n.If n is even, the problem can be solved by making the following move n times: turn over all the glasses except the ith glass, where i = 1, 2, . . . , n.
Here is an example of the algorithm’s application for n = 6. Let us denote the upside down glasses by 1’s and the others as 0’s. A glass that is not turned over on the next move is shown in bold.

If the value of i is 1, then turn over all the glasses except the 1st glass.
111111 –> 100000
Similarly, If the value of i is 2, then turn over all the glasses except the 2nd glass.
100000 –> 001111
Similarly, If the value of i is 3, then turn over all the glasses except the 3rd glass.
001111 –> 111000 and so on.
So, for n = 6, this will look like :

111111 –> 100000 –> 001111 –> 111000 –> 000011 –> 111110 –> 000000

Since any two consecutive moves will either have no impact on the state of the glasses or change the state of exactly two of them, no algorithm can solve the problem in fewer than n moves.

04
Round
Easy
HR Round
Duration30 Minutes
Interview date10 Oct 2015
Coding problem2

This was a typical HR round with some standard Behavioral questions.

1. Basic HR Question

Tell me something about yourself?

Problem approach

Tip 1 : Prepare the points that you will speak in your introduction prior to the interview.
Tip 2 : Tell about your current cgpa, achievements and authenticated certification
Tip 3 : I told about my role in current internship and what all I do

2. Basic HR Question

Why you want to be a part of Oracle?

Problem approach

Tip 1 : Oracle technologies are modern, cutting edge and built for enterprise requirements (think world class security, availability, performance, scalability, integrated ML/AI and so forth). Oracle Database is #1 worldwide. 
Tip 2 : Since it’s inception, Oracle has become a market leader when it comes to database. Oracle has its own all possible solution for it’s clients whether it is into IT or Banking.
Tip 3 : Oracle gives your job sustainability with better career growth - in terms of job profile and package both.

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Skill covered: Programming

How do you remove whitespace from the start of a string?

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