//---------------------------15/04/01----------------------------

//inplace_merge(要求有序)

template<class BidirectionalIterator>

inline void inplace_merge(BidirectionalIterator first,

BidirectionalIterator middle,

BidirectionalIterator last)

{

if(first == middle || middle == last)

return;

__inplace_merge_aux(first, middle, last, value_type(first),

distance_type(first));

}

template<class BidirectionalIterator,
class T, class Distance>

inline void __inplace_merge_aux(BidirectionalIterator first,

BidirectionalIterator middle,

BidirectionalIterator last,

T*, Distance*)

{

Distance len1 =
;

distance(first, middle, len1);

Distance len2 =
;

distance(middle, last, len2);

//用来申请暂时的缓冲区

temporary_buffer<BidirectionalIterator, T> buf(first, last);

)

__merge_without_buffer(first, middle, last, len1, len2);

else

__merge_adaptive(first, middle, last, len1, len2,

buf.begin(), Distance(buf.size()));

}

//有缓冲区的情况

template<class BidirectionalIterator,
class Distance, class Pointer>

void __merge_adaptive(BidirectionalIterator first,

BidirectionalIterator middle,

BidirectionalIterator last,

Distance len1, Distance len2,

Pointer buffer, Distance buffer_size)

{

if(len1 <= len2 && len1 <= buffer_size)

{

//先复制[first,middle)区间的元素到缓冲区

Pointer end_buffer = copy(first, middle, buffer);

//调用merge函数,把元素放入first开始的区间,也就是first到last

merge(buffer, end_buffer, middle, last, first);

}

else if(len2 <= buffer_size)

{

Pointer end_buffer = copy(middle, last, buffer);

//从后面开始merge。

__merge_backward(first, middle, buffer, end_buffer, last);

}

else

{

//缓冲区放不下len1
或 len2,需要进行裁剪

//搞不懂为什么前面是lower_bound,后面是upper_bound

//有一种可能是:len1 > len2时,取lower_bound可以使更少的元素换到左边的区间

//len1 < len2时,取upper_bound可以时更少的元素换到右边。

//这么做可以平衡两个区间的元素量

BidirectionalIterator first_cut =first;

BidirectionalIterator second_cut = middle;

Distance len11 =
;

Distance len22 =
;

if(len1 > len2)

{

len11 = len1 /
;

advance(first_cut, len11);

second_cut = lower_bound(middle, last, *first_cut);

distance(middle, second_cut, len22);

}

else

{

len22 = len2 /
;

advance(second_cut, len22);

first_cut = upper_bound(first, middle, *second_cut);

distance(first, first_cut, len11);

}

//到这时区间是这样的 first      first_cut        middle        second_cut      last

//为了让为了merge必须让要merge的区间并起来 
所以把middle到second_cut,换到first_cut的位置就可以了

//rotate后 first      first_cut(原middle)        new_middle(原first_cut)

//          second_cut(原second_cut)      last

BidirectionalIterator new_middle =

__rotate_adaptive(first_cut, middle, second_cut, len1 - len11,

len22, buffer, buffer_size);

__merge_adaptive(first, first_cut, new_middle, len11, len22, buffer,

buffer_size);

__merge_adaptive(new_middle, second_cut, last, len1 -len11,

len2 - len22, buffer, buffer_size);

}

}

template<class BidirectionalIterator1,
class BidirectionalIterator2,

class Distance>

BidirectionalIterator __rotate_adaptive(BidirectionalIterator1 first,

BidirectionalIterator1 middle,

BidirectionalIterator1 last,

Distance len1, Distance len2,

BidirectionalIterator2 buffer,

Distance buffer_size)

{

//缓冲区足够
就利用缓冲区翻转,不够就调用全局rotate

BidirectionalIterator2 buffer_end;

if(len1 > len2 && len2 <= buffer_size)

{

buffer_end = copy(middle, last, buffer);

copy_backward(first, middle, last);

return copy(buffer, buffer_end, first);

}

else if(len1 <= buffer_size)

{

buffer_end = copy(first, middle, buffer);

copy(middle, last, first);

return copy_backward(buffer, buffer_end, last);

}

else

{

rotate(first, middle, last);

advance(first, len2);

return first;

}

}

//nth_element

//使的nth的元素处在完全排序后的位置,只能保证这一个元素处在对的位置

template<class RandomAccessIterator>

inline void nth_element(RandomAccessIterator first,

RandomAccessIterator nth,

RandomAccessIterator last)

{

__nth_element(first, nth, last, value_type(first));

}

template<class RandomAccessIterator,
class T>

void __nth_element(RandomAccessIterator first,

RandomAccessIterator nth,

RandomAccessIterator last, T*)

{

)

{

//划分一次

RandomAccessIterator cut = __unguarded_partition

(first, last, T(__median(*first,

*(first + (last - first) /
),

*(last -
))));

//nth处在哪边就继续划分那边

if(cut <= nth)

first = cut;

else

last = cut;

}

__insertion_sort(first, last);

}

//merge sort

template<class BidirectionalIterator>

void mergesort(BidirectionalIterator first, BidirectionalIterator last)

{

typename iterator_traits<BidirectionalIterator>::difference_type n

=distance(first, last);

|| n ==
)

return;

else

{

BidirectionalIterator mid = first + n /
;

mergesort(first, mid);

mergesort(mid, last);

inplace_merge(first, mid, last);

}

}


stl源码剖析 详细学习笔记 算法(5)的更多相关文章

  1. stl源码剖析 详细学习笔记 算法(1)

    //---------------------------15/03/27---------------------------- //算法 { /* 质变算法:会改变操作对象之值 所有的stl算法都 ...

  2. stl源码剖析 详细学习笔记 算法总览

    //****************************基本算法***************************** /* stl算法总览,不在stl标准规格的sgi专属算法,都以 *加以标 ...

  3. stl源码剖析 详细学习笔记 算法(2)

    //---------------------------15/03/29---------------------------- //****************************set相 ...

  4. stl源码剖析 详细学习笔记 算法(4)

    //---------------------------15/03/31---------------------------- //lower_bound(要求有序) template<cl ...

  5. stl源码剖析 详细学习笔记 算法(3)

    //---------------------------15/03/30---------------------------- //min_element template<class Fo ...

  6. stl源码剖析 详细学习笔记 hashtable

    //---------------------------15/03/24---------------------------- //hashtable { /* 概述: sgi采用的是开链法完成h ...

  7. stl源码剖析 详细学习笔记 set map

    // //  set map.cpp //  笔记 // //  Created by fam on 15/3/23. // // //---------------------------15/03 ...

  8. stl源码剖析 详细学习笔记 RB_tree (2)

    //---------------------------15/03/22---------------------------- //一直好奇KeyOfValue是什么,查了下就是一个和仿函数差不多 ...

  9. stl源码剖析 详细学习笔记 RB_tree (1)

    // //  RB_tree_STL.cpp //  笔记 // //  Created by fam on 15/3/21. // // #include "RB_tree_STL.h&q ...

随机推荐

  1. C# 实现 JAVA AES加密解密[原创]

    以下是网上普遍能收到的JAVA AES加密解密方法. 因为里面用到了KeyGenerator 和 SecureRandom,但是.NET 里面没有这2个类.无法使用安全随机数生成KEY. 我们在接收J ...

  2. .Net 环境

    更多系统版本下载:https://www.microsoft.com/net/download VSCode :https://code.visualstudio.com/

  3. python基础学习24----使用pymysql连接mysql

    使用pymysql连接mysql 安装pymysql pymysql安装可以通过两种方式 使用pip安装 首先简单说一下pip的使用方法 获取帮助 pip --help 升级 pip pip inst ...

  4. MySQL压缩包zip安装

    看了网上好多种教程,自己尝试失败了好多次,最后总算弄好了,具体如下 zip下载地址:https://dev.mysql.com/downloads/mysql/ 之后点击No thanks, just ...

  5. centos中,tomcat项目创建文件的权限

    参考文章:https://cloud.tencent.com/info/5f02caa932fd6dbfc46a3bb01af135e0.html 我们在centos中输入umask,会看到输出002 ...

  6. Docker容器学习与分享10

    Docker容器向外提供服务 用分享04中的Nginx服务来试一下. 不过这次我直接用Nginx镜像创建容器,先下载Nginx镜像. [root@promote ~]# docker search n ...

  7. C++课堂作业_02_PAT1025.反转链表

    The 1st classwork of the C++ program 题目:PAT.1025.反转链表 github链接:Click Here mdzz,做完题目的第一感受= = 这道题的题意就是 ...

  8. python第三十九课——面向对象(二)之初始化属性

    设计Car类,初始化属性speed,提供一个run函数 import time class Car: def __init__(self,speed): self.speed=speed #将Road ...

  9. loli的搜索测试-5

    今天早上听说不放假感觉很sad,又听说要考试感觉更sad了,早读的时候Juan_feng表示即使考也不会考虫食算,结果上午并没有考试,就自己做了几道题.不得不说做题的决定实在是太明智了,做NOIP历年 ...

  10. AxisWebservice 发送多参数配置

    1.在web.xml中配置代码如下 <servlet> <servlet-name>AxisServlet</servlet-name> <display-n ...