Pairwise sorting-成对排序

The pairwise sorting network is a sorting network discovered and published by Ian Parberry in 1992 in Parallel Processing Letters.^[1] The pairwise sorting network has the same cost (number of comparators) and delay as the odd-even mergesort network.

Pairwise sorting network

Visualization of the Pairwise sorting network with 16 inputs
Class	Sorting algorithm
Data structure	Array
Worst-case performance	(log⁡n)(log⁡n+1)/2{\displaystyle (\log n)(\log n+1)/2} parallel time
Worst-case space complexity	n(log⁡n)(log⁡n−1)/4+n−1{\displaystyle n(\log n)(\log n-1)/4+n-1} non-parallel time

以上来自维基百科。

个人理解：

一、分组：

按照奇数偶数分组，长度减半。

两个sub-组 继续按奇数偶数分组，until 子组长度为1.

二、组合：

将分组排序，组合。