快速选择
Also known as Hoare's selection algorithm
In computer science, quickselect is a selection algorithm to find the kth smallest element in an unordered list, also known as the kth order statistic. Like the related quicksort sorting algorithm, it was developed by Tony Hoare, and thus is also known as '''Hoare's selection algorithm'''. Like quicksort, it is efficient in practice and has good average-case performance, but has poor worst-case performance. Quickselect and its variants are the selection algorithms most often used in efficient real-world implementations.
Key facts
- Algorithm.name
- Quickselect
- Algorithm.class
- Selection algorithm
- Algorithm.image
- Animated visualization of the quickselect algorithm. Selecting the 22st smallest value.
- Algorithm.caption
- Animated visualization of the quickselect algorithm. Selecting the 22nd smallest value.
- Algorithm.data
- Array
- Algorithm.best time
- O(n)
- Algorithm.average time
- O(n)
- Algorithm.time
- O(n2)
- Algorithm.space
- O(1)
via Wikipedia infobox
Wikidata facts
- Image
- Selecting quickselect frames.gif
via Wikidata · CC0
Article · 中文
在计算机科学中，快速选择（英語：Quickselect）是一种从无序列表找到第k小元素的选择算法。它从原理上来说与快速排序有关。与快速排序一样都由托尼·霍尔提出的，因而也被称为霍尔选择算法。 同样地，它在实际应用是一种高效的算法，具有很好的平均时间复杂度，然而最坏时间复杂度则不理想。快速选择及其变种是实际应用中最常使用的高效选择算法。 快速选择的总体思路与快速排序一致，选择一个元素作为基准来对元素进行分区，将小于和大于基准的元素分在基准左边和右边的两个区域。不同的是，快速选择并不递归访问双边，而是只递归进入一边的元素中继续寻找。这降低了平均时间复杂度，从O(n log n)至O(n)，不过最坏情况仍然是O(n2)。 与快速排序一样，快速选择一般是以原地算法的方式实现，除了选出第k小的元素，数据也得到了部分地排序。
Abstract from DBpedia / Wikipedia · CC BY-SA