RaRa Delivery Interview Questions and Answers

NP hardness refers to the difficulty of solving a problem in non-deterministic polynomial time.

• NP-hard problems are some of the most difficult problems in computer science.

• They cannot be solved in polynomial time by any known algorithm.

• Examples include the traveling salesman problem and the knapsack problem.

A reference variable is a variable that holds the memory address of an object, while an actual reference is the object itself.

• A reference variable is declared with a specific type and can only refer to objects of that type.

• An actual reference is the object itself, which can be accessed and manipulated using the reference variable.

• Changing the value of a reference variable does not affect the original object, but changi...read more

Discussing time complexities of data structures and algorithms is crucial for understanding performance in software development.

• Time complexity measures the amount of time an algorithm takes to complete as a function of the input size.

• Common complexities include O(1) for constant time, O(n) for linear time, and O(n^2) for quadratic time.

• For example, accessing an element in an array is O(1), while searching for an eleme...read more

The 0-1 Knapsack problem involves maximizing value within a weight limit using items that can either be included or excluded.

• Dynamic Programming approach is commonly used to solve this problem.

• Each item has a weight and a value; you cannot take fractional items.

• Example: If you have items with weights [1, 2, 3] and values [10, 15, 40], and a capacity of 6, the maximum value is 55.

• The solution involves creating a table t...read more

Typing a URL initiates a series of steps to retrieve and display the requested web page in the browser.

• 1. DNS Resolution: The browser checks the URL and queries a DNS server to translate the domain name into an IP address.

• 2. TCP Connection: A TCP connection is established with the server using the IP address, typically on port 80 (HTTP) or 443 (HTTPS).

• 3. Sending HTTP Request: The browser sends an HTTP request to the se...read more

Implement an LRU cache using a combination of a hashmap and a doubly linked list.

• Use a hashmap for O(1) access to cache items.

• Use a doubly linked list to maintain the order of usage.

• When adding a new item, check if the cache is full; if so, remove the least recently used item.

• Update the position of accessed items in the linked list to mark them as recently used.

• Example: For a cache size of 2, accessing keys 1, 2, then ...read more

Explaining page replacement algorithms like FIFO and LRU using a given page access sequence.

• FIFO (First-In-First-Out): Replaces the oldest page in memory.

• Example: Access sequence [1, 2, 3, 1, 2, 4] with 3 frames results in [1, 2, 4].

• LRU (Least Recently Used): Replaces the page that hasn't been used for the longest time.

• Example: Access sequence [1, 2, 3, 1, 2, 4] with 3 frames results in [2, 3, 4].

• Optimal: Replaces the ...read more

Indexing in DBMS improves data retrieval speed by creating a data structure that allows quick access to records.

• Indexing creates a data structure (like B-trees) that maps keys to their corresponding records.

• It speeds up search queries, reducing the time complexity from O(n) to O(log n) in many cases.

• Types of indexes include primary, unique, composite, and full-text indexes.

• Example: A primary index on a student ID allow...read more

Given a list of process IDs and their corresponding parent process IDs, print the IDs of all processes that are children of a specific process ID, and recursively kill all their children.

• Iterate through the list of process IDs and parent process IDs

• Check if the current process ID is the one to be killed

• If yes, recursively find and print all its children

• If a child has further children, recursively kill them as well