lec16 - Dictionaries Collection of items Each item is a...

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Dictionaries Collection of items. Each item is a pair. (key, element) Pairs have different keys.
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Application Collection of student records in this class. (key, element) = (student name, linear list of assignment and exam scores) All keys are distinct. Collection of in-use domain names. (godaddy.com, owner information) All keys are distinct.
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Dictionary With Duplicates Keys are not required to be distinct. Word dictionary. Pairs are of the form (word, meaning) . May have two or more entries for the same word. (bolt, a threaded pin) (bolt, a crash of thunder) (bolt, to shoot forth suddenly) (bolt, a gulp) (bolt, a standard roll of cloth) etc.
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Dictionary Operations Static Dictionary. initialize/create get(theKey) (a.k.a. search ) CD ROM word dictionary CD ROM geographic database of cities, rivers, roads, auto navigation system, etc. Dynamic Dictionary. get(theKey) (a.k.a. search ) put(theKey, theElement) (a.k.a. insert ) remove(theKey) (a.k.a. delete )
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Hash Table Dictionaries O(1) expected time for get , put , and remove .
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