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## Boost.Sort

### Steven Ross

### Francisco Tapia

### Orson Peters

Copyright © 2014-2017 Steven Ross, Francisco Tapia, Orson Peters

Distributed under the Boost Software License, Version 1.0.

## 1.- Introduction

> The goal of the Boost Sort Library is provide to the users, the most modern, fast, and memory-efficient sorting algorithms.

> This library provides stable and unstable sorting algorithms, in single threaded and parallel versions.

> These algorithms do not use any other library or utility, you only need to include boost/sort/sort.hpp or one of the more specific headers. The parallel algorithms need a C++11 compliant compiler.

> ##### Single Thread Algorithms

>                       |       |                            |                                            | Comparison          |
>     Algorithm         |Stable |   Additional memory        |Best, average, and worst case               | method              |
>     ------------------+-------+----------------------------+--------------------------------------------+---------------------+
>     spreadsort        |  no   |      key_length            | N, N sqrt(LogN), min(N logN, N key_length) | Hybrid radix sort   |
>     pdqsort           |  no   |      Log N                 | N, N LogN, N LogN                          | Comparison operator |
>     spinsort          |  yes  |      N / 2                 | N, N LogN, N LogN                          | Comparison operator |
>     flat_stable_sort  |  yes  |size of the data / 256 + 8K | N, N LogN, N LogN                          | Comparison operator |
>                       |       |                            |                                            |                     |

> - spreadsort is an extremely fast hybrid radix sort algorithm, designed and developed by Steven Ross.
> - pdqsort is a improvement of the quick sort algorithm, designed and developed by Orson Peters.
> - spinsort is a stable sort that is fast with random or nearly sorted data, designed and developed by Francisco Tapia.
> - flat_stable_sort is a stable sort that uses very little additional memory (around 1% of the size of the data), providing 80% - 90% of the speed of spinsort, designed and developed by Francisco Tapia.

> ##### Parallel Algorithms

>                           |       |                        |                              |
>     Algorithm             |Stable |   Additional memory    |Best, average, and worst case |
>     ----------------------+-------+------------------------+------------------------------+
>     block_indirect_sort   |  no   |block_size * num_threads| N, N LogN , N LogN           |
>     sample_sort           |  yes  |        N               | N, N LogN , N LogN           |
>     parallel_stable_sort  |  yes  |      N / 2             | N, N LogN , N LogN           |
>                           |       |                        |                              |

> - Sample_sort is a implementation of the Samplesort algorithm done by Francisco Tapia.
> - Parallel_stable_sort is based on the samplesort algorithm, but using a half of the memory used by sample_sort, conceived and implemented by Francisco Tapia.
> - Block_indirect_sort is a novel high-speed parallel sort algorithm with low additional memory consumption, conceived and implemented by Francisco Tapia.

> The block_size is an internal parameter of the algorithm, which in order to achieve the highest speed, changes according to the size of the objects to sort according to the next table. The strings use a block_size of 128.

>                                     |        |         |         |         |         |         |          |
>     object size (bytes)             | 1 - 15 | 16 - 31 | 32 - 63 | 64 - 127|128 - 255|256 - 511| 512 -    |
>     --------------------------------+--------+---------+---------+---------+---------+---------+----------+
>     block_size (number of elements) |  4096  |  2048   |   1024  |   768   |   512   |   256   |  128     |
>                                     |        |         |         |         |         |         |          |