SDE - Intern

You have been given two strings, 'str1' and 'str2'.

Your task is to return true if the given two strings are isomorphic to each other, else return false.

Note :

Two strings are isomorphic if a one-to-one mapping is possible for every character of the first string ‘str1’ to every character of the second string ‘str2’ while preserving the order of the characters.

All occurrences of every character in the first string ‘str1’ should map to the same character in the second string, ‘str2’.

For example :

If str1 = “aab” and str2 = “xxy” then the output will be 1. ‘a’ maps to ‘x’ and ‘b’ maps to ‘y’.

If str1 = “aab” and str2 = “xyz” then the output will be 0. There are two different characters in 'str1', while there are three different characters in 'str2'. So there won't be one to one mapping between 'str1' and 'str2'.

You are given an array ‘ARR’ having ‘N’ integers. You are also given an integer ‘K’. The task is to count the number of subarrays that have ‘K’ distinct values.

Subarray: A consecutive sequence of one or more values taken from an array.

For Example :

‘N’ = 4, ‘K’ = 2
‘ARR’ = [1, 1, 2, 3]

There are ‘3’ subarrays with ‘2’ distinct elements, which are as follows: [1, 2], [2, 3], [1, 1, 2].
Thus, you should return ‘3’ as the answer.

Find employees who earn more than their managers.

Each employee may have a manager, and the managerId refers to the id of another employee in the same table.

Write an SQL query to find the names of employees whose salary is greater than their manager’s salary. (Practice)

You're given a string 'S' consisting of "{", "}", "(", ")", "[" and "]" .

Return true if the given string 'S' is balanced, else return false.

For example:

'S' = "{}()".

There is always an opening brace before a closing brace i.e. '{' before '}', '(' before ').
So the 'S' is Balanced.

• What are abstract classes, and how do they differ from interfaces? (Learn)
• What is the difference between composition and inheritance? (Learn)
• What is the difference between shallow copy and deep copy? (Learn)
• What is the Rule of Three / Rule of Five in object-oriented programming?
• What are constructors and destructors, and when are they called? (Learn)
• What is object slicing, and when does it occur?
• What is the difference between static binding and dynamic binding? (Learn)
• What is the Liskov Substitution Principle (LSP) in OOP? (Learn)
• What are the SOLID principles in object-oriented design?

• How do deadlock detection, prevention, and avoidance differ? Explain Banker’s Algorithm.
• What are semaphores, and how are they used to solve the producer–consumer problem?
• Explain the difference between a mutex, a semaphore, and a monitor.
• What are page replacement algorithms? Explain LRU, FIFO, and Optimal. (Learn)

• What is the difference between a clustered index and a non-clustered index? (Learn)
• What are B-Trees and B+ Trees, and why are they used in databases? (Learn)
• What is the difference between horizontal and vertical partitioning?
• What is MVCC (Multi-Version Concurrency Control), and how does it work?
• Explain write-ahead logging (WAL) and its role in recovery.
• What is the difference between serializable and snapshot isolation levels?

Given two sorted arrays 'a' and 'b' of size 'n' and 'm' respectively.

Find the median of the two sorted arrays.

Median is defined as the middle value of a sorted list of numbers. In case the length of list is even, median is the average of the two middle elements.

The expected time complexity is O(min(logn, logm)), where 'n' and 'm' are the sizes of arrays 'a' and 'b', respectively, and the expected space complexity is O(1).

Example:

Input: 'a' = [2, 4, 6] and 'b' = [1, 3, 5]

Output: 3.5

Explanation: The array after merging 'a' and 'b' will be { 1, 2, 3, 4, 5, 6 }. Here two medians are 3 and 4. So the median will be the average of 3 and 4, which is 3.5.