C questions

Context switching is the process of saving the state of a currently running process and loading the state of the next process to be executed. It involves saving registers, program counter, and other context information. For example, switching between multiple applications on a computer involves context switching.

A race condition occurs when the outcome of a process depends on the sequence or timing of uncontrollable events. It can lead to unpredictable results. To prevent race conditions, synchronization mechanisms like mutexes and semaphores are used to ensure orderly access to shared resources.

A file descriptor is an integer handle used by the OS to access files and I/O resources. It is returned by system calls like 'open' and used in subsequent operations such as 'read' or 'write'. For example, in Unix-like systems, file descriptor 0 refers to standard input.

Interrupt requests (IRQs) are signals sent to the CPU indicating that a device needs attention. IRQs help manage hardware communication and prioritize tasks. For instance, pressing a key on the keyboard generates an IRQ to notify the OS to read the keystroke.

Cloud computing is the delivery of computing services, such as storage, processing power, and applications, over the internet. This eliminates the need for local servers or personal devices. For example, services like Google Drive and Dropbox store files in the cloud, allowing users to access them from anywhere.

A compiler is a program that translates source code written in a high-level programming language (such as C++ or Java) into machine code that a computer can execute. For example, the GNU C Compiler (GCC) compiles C code into executable machine instructions that the CPU can understand.

Use a hash map to count the frequency of each character, then iterate through the string to find the first character with a count of 1. For example, in 'swiss', the first non-repeating character is 'w'.

Use a dynamic programming approach to build a table that tracks palindromic substrings. For example, in 'babad', the longest palindromic substring is 'bab' or 'aba'.

Binary search divides the search interval in half. Start with the middle element; if it matches the target, return it. Otherwise, adjust the search range to either the left or right half based on comparison. For example, searching for 4 in [1, 2, 3, 4, 5] returns index 3.

DFS explores as far as possible along each branch before backtracking. Use a stack or recursion to keep track of nodes. For example, in a graph with nodes 1 -> 2 -> 3, DFS from 1 explores 1, 2, and then 3.

BFS explores all neighbors of a node before moving to the next level. Use a queue to keep track of nodes. For example, in a graph with nodes 1 -> 2 -> 3, BFS from 1 explores 1, then 2 and 3.

Use Depth-First Search with a tracking mechanism for visited nodes. If a node is revisited during the same DFS traversal, a cycle exists. For example, in a graph with edges 1 -> 2 -> 3 -> 1, a cycle is detected.

A priority queue can be implemented using a heap where the highest (or lowest) priority element is always at the top. Operations include insert and extract-max (or extract-min). For example, in a max-heap, inserting 5 and 10 results in [10, 5].

Use dynamic programming to build a table where each cell represents the length of the longest common subsequence up to those indices. For example, for 'abcde' and 'aceb', the longest common subsequence is 'ace' with length 3.

Use Kadane's Algorithm to find the maximum sum. Initialize the maximum sum and current sum as the first element, then iterate through the array updating these values. For example, for [1, -2, 3, 4, -1], the maximum subarray sum is 7.

Use two pointers to traverse the linked lists. When one pointer reaches the end, move it to the start of the other list. Continue until both pointers meet. For example, if lists intersect at node with value 8, both pointers will eventually reach this node.

Use topological sorting to order nodes and then apply dynamic programming to find the longest path. For example, in a DAG with edges 1 -> 2, 1 -> 3, 2 -> 4, 3 -> 4, the longest path is 1 -> 2 -> 4 or 1 -> 3 -> 4.

Use a sliding window and hash maps to compare character counts. Slide the window across the string and check if the counts match. For example, in 'cbaebabacd' with pattern 'abc', the start indices of anagrams are 0 and 6.

HTML5 is the fifth version of the HTML standard. It introduces new elements, attributes, and behaviors, enhancing the language's capability to create more dynamic and interactive web content. For example, `<article>` and `<section>` elements are used for better semantic structuring.

Semantic elements provide meaning to the web content, improving accessibility and SEO. Elements like `<header>`, `<footer>`, and `<article>` make the structure of web pages more understandable to both browsers and developers.

The `<section>` element represents a thematic grouping of content, typically with a heading. It's used to divide a webpage into logical sections. For instance, `<section>` can be used to group related content such as different articles or parts of a webpage.

The `<article>` element represents a self-contained piece of content that could be distributed independently. Examples include blog posts, news articles, or user comments. It should ideally contain a heading and content related to the heading.

The `<aside>` element is used for content that is tangentially related to the content around it, such as sidebars, pull quotes, or advertisements. It helps to separate supplementary content from the main content, improving page structure and accessibility.

The `<header>` element typically contains introductory content or navigational aids, like headings or logo. Conversely, the `<footer>` element usually contains metadata about the section it is in, such as copyright information or contact details.

`grid-template-areas` defines named grid areas within a grid container. It uses a string to assign names to specific grid cells. For example, `grid-template-areas: 'header header' 'sidebar content' 'footer footer';` creates a layout with named regions.