// Filename: stl_heap.h
// Comment By: 凝霜
// E-mail: [email protected]
// Blog: http://blog.csdn.net/mdl13412
/*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
* Copyright (c) 1997
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/
/* NOTE: This is an internal header file, included by other STL headers.
* You should not attempt to use it directly.
*/
#ifndef __SGI_STL_INTERNAL_HEAP_H
#define __SGI_STL_INTERNAL_HEAP_H
__STL_BEGIN_NAMESPACE
#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma set woff 1209
#endif
// 注意: push_heap()操作前要保证新添加的元素已经加入到容器末尾!!!
// 下面是使用默认比较函数的一个实例, XXX代表需要调整结点的位置
// 执行插入前, 元素已经追加到容器尾, 其值为450, 这里我们只
// 关注其位置, 不表示出其数值
// [500]
// |
// ---------------------------------
// | |
// [300] [400]
// | |
// ----------------------- -----------------------
// | | | |
// [200] [270] [350] [240]
// | |
// ----------- -----------
// | | | |
// [150] [130] [120] [XXX]
//
// first last
// ↓ ↓
// --------------------------------------------------------------------------------------------
// | Not Use | 500 | 300 | 400 | 200 | 270 | 350 | 240 | 150 | 130 | 120 | XXX | ...... | end |
// --------------------------------------------------------------------------------------------
//
// 下面是移动步骤及内存变化
// [500]
// |
// ---------------------------------
// | |
// [300] [400]
// | |
// ----------------------- -----------------------
// | | | |
// [200] [XXX]------- [350] [240]
// | | |
// ----------- ----------- |
// | | | | | 调整元素位置
// [150] [130] [120] [270]--
//
// first last
// ↓ ↓
// --------------------------------------------------------------------------------------------
// | Not Use | 500 | 300 | 400 | 200 | XXX | 350 | 240 | 150 | 130 | 120 | 270 | ...... | end |
// --------------------------------------------------------------------------------------------
//
// [500]
// |
// ---------------------------------
// | |
// [XXX]------------- 交换 [400]
// | | |
// ----------------------- | -----------------------
// | | | | |
// [200] [300]-- [350] [240]
// | |
// ----------- -----------
// | | | |
// [150] [130] [120] [270]
//
// first last
// ↓ ↓
// --------------------------------------------------------------------------------------------
// | Not Use | 500 | XXX | 400 | 200 | 300 | 350 | 240 | 150 | 130 | 120 | 270 | ...... | end |
// --------------------------------------------------------------------------------------------
//
// 现在满足heap的要求了, 对[XXX]直接赋值即可
//
template
void __push_heap(RandomAccessIterator first, Distance holeIndex,
Distance topIndex, T value)
{
// 首先找出待处理元素的父结点
Distance parent = (holeIndex - 1) / 2;
// 判断当前待处理结点是否优先级高于其父结点, 如果是则将其父结点向下移动
// 设置当前结点为父结点位置, 继续, 直到优先级小于父结点或者已经到达heap顶端
while (holeIndex > topIndex && *(first + parent) < value) {
*(first + holeIndex) = *(first + parent);
holeIndex = parent;
parent = (holeIndex - 1) / 2;
}
// 将找到的合适的位置设置成正确值
*(first + holeIndex) = value;
}
template
inline void __push_heap_aux(RandomAccessIterator first,
RandomAccessIterator last, Distance*, T*)
{
// 因为first所指的那个元素不是heap的组成元素, 所以计算距离要减去1
__push_heap(first, Distance((last - first) - 1), Distance(0),
T(*(last - 1)));
}
// 调用此函数前要先把待处理元素追加到容器末尾
template
inline void push_heap(RandomAccessIterator first, RandomAccessIterator last)
{
__push_heap_aux(first, last, distance_type(first), value_type(first));
}
template
void __push_heap(RandomAccessIterator first, Distance holeIndex,
Distance topIndex, T value, Compare comp)
{
Distance parent = (holeIndex - 1) / 2;
while (holeIndex > topIndex && comp(*(first + parent), value)) {
*(first + holeIndex) = *(first + parent);
holeIndex = parent;
parent = (holeIndex - 1) / 2;
}
*(first + holeIndex) = value;
}
template
inline void __push_heap_aux(RandomAccessIterator first,
RandomAccessIterator last, Compare comp,
Distance*, T*)
{
__push_heap(first, Distance((last - first) - 1), Distance(0),
T(*(last - 1)), comp);
}
// 这个除了用户自己指定优先级决策判别式外和默认的无区别
template
inline void push_heap(RandomAccessIterator first, RandomAccessIterator last,
Compare comp)
{
__push_heap_aux(first, last, comp, distance_type(first), value_type(first));
}
// 注意: pop_heap()操作, 执行完操作后要自己将容器尾元素弹出
// 这里以默认的heap优先级决策来说
// STL采用的是先将待pop的元素复制到heap尾部, 然后将整个heap向上调整
// 这样就会将最后空出一个hole, 将原来最后的元素在这里进行push()操作
// 这就是两个shift_up的过程
// 个人感觉使用使用shift_down的算法更高效, 虽然时间复杂度一样, 但是shift_down
// 进行操作的元素会更少,
// 之所以用shift_up这可能也是STL设计理念的问题吧, 能复用就不写新的^_^
// 下面是使用默认比较函数的一个实例, 我们要弹出的是优先级最高的元素[500]
// 首先要把弹出的元素[500]复制到heap末尾
// 然后进行第一次shift_up, 完成后进行push()操作, 这个就是第二次shift_up了
//
// [500]
// |
// ---------------------------------
// | |
// [300] [400]
// | |
// ----------------------- -----------------------
// | | | |
// [200] [270] [350] [240]
// | |
// ----------- -----------
// | | | |
// [150] [130] [120] [100]
//
// first last
// ↓ ↓
// --------------------------------------------------------------------------------------------
// | Not Use | 500 | 300 | 400 | 200 | 270 | 350 | 240 | 150 | 130 | 120 | 100 | ...... | end |
// --------------------------------------------------------------------------------------------
//
// 下面是移动步骤及内存变化 复制
// [500]----------------------------------
// | |
// --------------------------------- |
// | | |
// [300] [400] |
// | | |
// ----------------------- ----------------------- |
// | | | | |
// [200] [270] [350] [240] |
// | | |
// ----------- ----------- |
// | | | | |
// [150] [130] [120] [500]----------------------------------
//
// first last
// ↓ ↓
// --------------------------------------------------------------------------------------------
// | Not Use | 500 | 300 | 400 | 200 | 270 | 350 | 240 | 150 | 130 | 120 | 500 | ...... | end |
// --------------------------------------------------------------------------------------------
//
// [400]-----------------------
// | |
// --------------------------------- | shift_up
// | | |
// [300] [400]-------
// | |
// ----------------------- -----------------------
// | | | |
// [200] [270] [350] [240]
// | |
// ----------- -----------
// | | | |
// [150] [130] [120] [500]
//
// first last
// ↓ ↓
// --------------------------------------------------------------------------------------------
// | Not Use | 400 | 300 | 400 | 200 | 270 | 350 | 240 | 150 | 130 | 120 | 500 | ...... | end |
// --------------------------------------------------------------------------------------------
//
// [400]
// |
// ---------------------------------
// | | shift_up
// [300] [350]-------------------
// | | |
// ----------------------- ----------------------- |
// | | | | |
// [200] [270] [350] [240] |
// | | | |
// ----------- ----------- ----------------------------------
// | | | |
// [150] [130] [120] [500]
//
// first last
// ↓ ↓
// --------------------------------------------------------------------------------------------
// | Not Use | 400 | 300 | 350 | 200 | 270 | 350 | 240 | 150 | 130 | 120 | 500 | ...... | end |
// --------------------------------------------------------------------------------------------
//
// 接下来就是push()操作了, 参考前面的push()
template
void __adjust_heap(RandomAccessIterator first, Distance holeIndex,
Distance len, T value)
{
Distance topIndex = holeIndex;
Distance secondChild = 2 * holeIndex + 2; // 弹出元素的有子孩
// 调整heap元素位置
while (secondChild < len) {
// 选择两个子孩中较大的进行操作, 使用secondChild表示其偏移
if (*(first + secondChild) < *(first + (secondChild - 1)))
secondChild--;
// 将较大元素向上填充, 并将整体偏移向下调整, 继续调整
*(first + holeIndex) = *(first + secondChild);
holeIndex = secondChild;
secondChild = 2 * (secondChild + 1);
}
if (secondChild == len) {
*(first + holeIndex) = *(first + (secondChild - 1));
holeIndex = secondChild - 1;
}
// 这里就是shift_up过程了, 将最初的heap末尾元素向上调整
// 侯捷老师对这里的理解有误, :-), 人非圣贤, 孰能无过, ^_^
__push_heap(first, holeIndex, topIndex, value);
}
template
inline void __pop_heap(RandomAccessIterator first, RandomAccessIterator last,
RandomAccessIterator result, T value, Distance*)
{
// 将弹出的元素调整到heap末尾, 这个元素需要用户手动弹出
*result = *first;
// 去掉末尾哪个弹出的元素, 调整heap
__adjust_heap(first, Distance(0), Distance(last - first), value);
}
template
inline void __pop_heap_aux(RandomAccessIterator first,
RandomAccessIterator last, T*)
{
__pop_heap(first, last - 1, last - 1, T(*(last - 1)), distance_type(first));
}
template
inline void pop_heap(RandomAccessIterator first, RandomAccessIterator last)
{
__pop_heap_aux(first, last, value_type(first));
}
template
void __adjust_heap(RandomAccessIterator first, Distance holeIndex,
Distance len, T value, Compare comp)
{
Distance topIndex = holeIndex;
Distance secondChild = 2 * holeIndex + 2;
while (secondChild < len) {
if (comp(*(first + secondChild), *(first + (secondChild - 1))))
secondChild--;
*(first + holeIndex) = *(first + secondChild);
holeIndex = secondChild;
secondChild = 2 * (secondChild + 1);
}
if (secondChild == len) {
*(first + holeIndex) = *(first + (secondChild - 1));
holeIndex = secondChild - 1;
}
__push_heap(first, holeIndex, topIndex, value, comp);
}
template
inline void __pop_heap(RandomAccessIterator first, RandomAccessIterator last,
RandomAccessIterator result, T value, Compare comp,
Distance*)
{
*result = *first;
__adjust_heap(first, Distance(0), Distance(last - first), value, comp);
}
template
inline void __pop_heap_aux(RandomAccessIterator first,
RandomAccessIterator last, T*, Compare comp)
{
__pop_heap(first, last - 1, last - 1, T(*(last - 1)), comp,
distance_type(first));
}
template
inline void pop_heap(RandomAccessIterator first, RandomAccessIterator last,
Compare comp)
{
__pop_heap_aux(first, last, value_type(first), comp);
}
// 这个没设么好说的, 参考上面的分析吧
template
void __make_heap(RandomAccessIterator first, RandomAccessIterator last, T*,
Distance*)
{
if (last - first < 2) return;
Distance len = last - first;
Distance parent = (len - 2)/2;
while (true) {
__adjust_heap(first, parent, len, T(*(first + parent)));
if (parent == 0) return;
parent--;
}
}
template
inline void make_heap(RandomAccessIterator first, RandomAccessIterator last)
{
__make_heap(first, last, value_type(first), distance_type(first));
}
template
void __make_heap(RandomAccessIterator first, RandomAccessIterator last,
Compare comp, T*, Distance*)
{
if (last - first < 2) return;
Distance len = last - first;
Distance parent = (len - 2)/2;
while (true) {
__adjust_heap(first, parent, len, T(*(first + parent)), comp);
if (parent == 0) return;
parent--;
}
}
template
inline void make_heap(RandomAccessIterator first, RandomAccessIterator last,
Compare comp)
{
__make_heap(first, last, comp, value_type(first), distance_type(first));
}
// 这个能保证heap有序, 其实个人感觉没啥必要, 这样还不如直接用平衡二叉树
template
void sort_heap(RandomAccessIterator first, RandomAccessIterator last)
{
while (last - first > 1) pop_heap(first, last--);
}
template
void sort_heap(RandomAccessIterator first, RandomAccessIterator last,
Compare comp)
{
while (last - first > 1) pop_heap(first, last--, comp);
}
#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma reset woff 1209
#endif
__STL_END_NAMESPACE
#endif /* __SGI_STL_INTERNAL_HEAP_H */
// Local Variables:
// mode:C++
// End:
