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最新推荐文章于 2019-09-09 21:18:00 发布

原创最新推荐文章于 2019-09-09 21:18:00 发布 · 716 阅读

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#table #structure

本文介绍了哈希表作为一种高效查找表的特点，包括快速查找、与列表的不同之处、无特定顺序以及无法共享结构等关键信息。

　A hash table is a very fast kind of lookup table, somewhat like an
alist in that it maps keys to corresponding values. It differs from an
alist in these ways:

   * Lookup in a hash table is extremely fast for large tables--in
     fact, the time required is essentially _independent_ of how many
     elements are stored in the table. For smaller tables (a few tens
     of elements) alists may still be faster because hash tables have a
     more-or-less constant overhead.

* The correspondences in a hash table are in no particular order.

* There is no way to share structure between two hash tables, the
way two alists can share a common tail.