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K-sorted Sequence
In computer science, a nearly-sorted sequence, also known as roughly-sorted sequence and as k-sorted sequence is a sequence which is almost ordered. By almost ordered, it is meant that no element of the sequence is very far away from where it would be if the sequence were perfectly ordered. It is still possible that no element of the sequence is at the place where it should be if the sequence were perfectly ordered. The nearly-sorted sequences are particularly useful when the exact order of element has little importance. For example Twitter nearly sort the tweets, up to the second, as there is no need for more precision. Actually, given the impossibility to exactly synchronize all computers, an exact sorting of all tweets according to the time at which they are posted is impossible. This idea led to the creation of Snowflake IDs. k-sorting is the operation of reordering the elements of a sequence so that it becomes k-sorted. k-sorting is generally more efficient than sorting. Sim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical disciplines (including the design and implementation of Computer architecture, hardware and Computer programming, software). Computer science is generally considered an area of research, academic research and distinct from computer programming. Algorithms and data structures are central to computer science. The theory of computation concerns abstract models of computation and general classes of computational problem, problems that can be solved using them. The fields of cryptography and computer security involve studying the means for secure communication and for preventing Vulnerability (computing), security vulnerabilities. Computer graphics (computer science), Computer graphics and computational geometry address the generation of images. Progr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Twitter
Twitter is an online social media and social networking service owned and operated by American company Twitter, Inc., on which users post and interact with 280-character-long messages known as "tweets". Registered users can post, like, and 'Reblogging, retweet' tweets, while unregistered users only have the ability to read public tweets. Users interact with Twitter through browser or mobile Frontend and backend, frontend software, or programmatically via its APIs. Twitter was created by Jack Dorsey, Noah Glass, Biz Stone, and Evan Williams (Internet entrepreneur), Evan Williams in March 2006 and launched in July of that year. Twitter, Inc. is based in San Francisco, California and has more than 25 offices around the world. , more than 100 million users posted 340 million tweets a day, and the service handled an average of 1.6 billion Web search query, search queries per day. In 2013, it was one of the ten List of most popular websites, most-visited websites and has been de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snowflake ID
Snowflake IDs, or snowflakes, are a form of unique identifier used in distributed computing. The format was created by Twitter and is used for the IDs of tweets. The format has been adopted by other companies, including Discord and Instagram. The Mastodon social network uses a modified version. Format Snowflakes are 64 bits in binary. (Only 63 are used to fit in a signed integer.) The first 41 bits are a timestamp, representing milliseconds since the chosen epoch. The next 10 bits represent a machine ID, preventing clashes. Twelve more bits represent a per-machine sequence number, to allow creation of multiple snowflakes in the same millisecond. The final number is generally serialized in decimal. Snowflakes are sortable by time, because they are based on the time they were created. Additionally, the time a snowflake was created can be calculated from the snowflake. This can be used to get snowflakes (and their associated objects) that were created before or after a particula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measure Of Presortedness
Measure may refer to: * Measurement, the assignment of a number to a characteristic of an object or event Law * Ballot measure, proposed legislation in the United States * Church of England Measure, legislation of the Church of England * Measure of the National Assembly for Wales, primary legislation in Wales * Assembly Measure of the Northern Ireland Assembly (1973) Science and mathematics * Measure (data warehouse), a property on which calculations can be made * Measure (mathematics), a systematic way to assign a number to each suitable subset of that set * Measure (physics), a way to integrate over all possible histories of a system in quantum field theory * Measure (termination), in computer program termination analysis * Measuring coalgebra, a coalgebra constructed from two algebras * Measure (Apple), an iOS augmented reality app Other uses * ''Measure'' (album), by Matt Pond PA, 2000, and its title track * Measure (bartending) or jigger, a bartending tool ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Time
In computer science, the time complexity is the computational complexity that describes the amount of computer time it takes to run an algorithm. Time complexity is commonly estimated by counting the number of elementary operations performed by the algorithm, supposing that each elementary operation takes a fixed amount of time to perform. Thus, the amount of time taken and the number of elementary operations performed by the algorithm are taken to be related by a constant factor. Since an algorithm's running time may vary among different inputs of the same size, one commonly considers the worst-case time complexity, which is the maximum amount of time required for inputs of a given size. Less common, and usually specified explicitly, is the average-case complexity, which is the average of the time taken on inputs of a given size (this makes sense because there are only a finite number of possible inputs of a given size). In both cases, the time complexity is generally expresse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Complexity
The space complexity of an algorithm or a computer program is the amount of memory space required to solve an instance of the computational problem as a function of characteristics of the input. It is the memory required by an algorithm until it executes completely. Similar to time complexity, space complexity is often expressed asymptotically in big O notation, such as O(n), O(n\log n), O(n^\alpha), O(2^n), etc., where is a characteristic of the input influencing space complexity. Space complexity classes Analogously to time complexity classes DTIME(f(n)) and NTIME(f(n)), the complexity classes DSPACE(f(n)) and NSPACE(f(n)) are the sets of languages that are decidable by deterministic (respectively, non-deterministic) Turing machines that use O(f(n)) space. The complexity classes PSPACE and NPSPACE allow f to be any polynomial, analogously to P and NP. That is, :\mathsf = \bigcup_ \mathsf(n^c) and :\mathsf = \bigcup_ \mathsf(n^c) Relationships between classes The space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streaming Algorithm
In computer science, streaming algorithms are algorithms for processing data streams in which the input is presented as a sequence of items and can be examined in only a few passes (typically just one). In most models, these algorithms have access to limited memory (generally logarithmic in the size of and/or the maximum value in the stream). They may also have limited processing time per item. These constraints may mean that an algorithm produces an approximate answer based on a summary or "sketch" of the data stream. History Though streaming algorithms had already been studied by Munro and Paterson as early as 1978, as well as Philippe Flajolet and G. Nigel Martin in 1982/83, the field of streaming algorithms was first formalized and popularized in a 1996 paper by Noga Alon, Yossi Matias, and Mario Szegedy. For this paper, the authors later won the Gödel Prize in 2005 "for their foundational contribution to streaming algorithms." There has since been a large body of work cen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
