Алгоритм сжатия Deflation #616290

Народ, у меня через 15 минут защита, сижу прорабатываю вопросы которые могут задать, Deflation в сжатии данных как работает? Ниче нормального не могу нагуглить.

Не судьба тебе видать стать дипломированным спецом раз нагуглить не можешь... сантехником будешь )

акцентируй внимание комиссии на важности этого алгоритма широкой применимости подорбных алгоритмов в науке и технике и т.п. не забудь упомянуть раз 10 модернизацию интенсификацию и нанотехнологии

дайте ссылку где есть принцип работы)

Расскажи про DES или ARS какойнить один хрен старпёры экзаменаторы ничё не рубят...

The deflation algorithm used by gzip (also zip and zlib) is a variation of LZ77 (Lempel-Ziv 1977, see reference below). It finds duplicated strings in the input data.  The second occurrence of a string is replaced by a pointer to the previous string, in the form of a pair (distance, length).  Distances are limited to 32K bytes, and lengths are limited to 258 bytes. When a string does not occur anywhere in the previous 32K bytes, it is emitted as a sequence of literal bytes.  (In this description, `string' must be taken as an arbitrary sequence of bytes, and is not restricted to printable characters.) Literals or match lengths are compressed with one Huffman tree, and match distances are compressed with another tree. The trees are stored in a compact form at the start of each block. The blocks can have any size (except that the compressed data for one block must fit in available memory). A block is terminated when deflate determines that it would be useful to start another block with fresh trees. (This is somewhat similar to the behavior of LZW-based _compress_.) Duplicated strings are found using a hash table. All input strings of length 3 are inserted in the hash table. A hash index is computed for the next 3 bytes. If the hash chain for this index is not empty, all strings in the chain are compared with the current input string, and the longest match is selected. The hash chains are searched starting with the most recent strings, to favor small distances and thus take advantage of the Huffman encoding. The hash chains are singly linked. There are no deletions from the hash chains, the algorithm simply discards matches that are too old. To avoid a worst-case situation, very long hash chains are arbitrarily truncated at a certain length, determined by a runtime option (level parameter of deflateInit). So deflate does not always find the longest possible match but generally finds a match which is long enough. deflate also defers the selection of matches with a lazy evaluation mechanism. After a match of length N has been found, deflate searches for a longer match at the next input byte. If a longer match is found, the previous match is truncated to a length of one (thus producing a single literal byte) and the process of lazy evaluation begins again. Otherwise, the original match is kept, and the next match search is attempted only N steps later. The lazy match evaluation is also subject to a runtime parameter. If the current match is long enough, deflate reduces the search for a longer match, thus speeding up the whole process. If compression ratio is more important than speed, deflate attempts a complete second search even if the first match is already long enough. The lazy match evaluation is not performed for the fastest compression modes (level parameter 1 to 3). For these fast modes, new strings are inserted in the hash table only when no match was found, or when the match is not too long. This degrades the compression ratio but saves time since there are both fewer insertions and fewer searches.

Ладно просто умолчу о том что сжимаю данные

Задай тон экзамену. Используй слово "Defloration"

+ но это фэйл если ты не смог найти

в общем.. читай.

кстати, если написал в дипломе Deflation, то это неправильно

бугага :))))))))

Deflation - чоткий алгоритм

фраза дня!

Все, защитил бакланку :) 88 баллов.

Проставляйся.

У нас сейчас тут 20 человек будет проставляться... живым не выберусь :0