473,890 Members | 2,051 Online
Bytes | Software Development & Data Engineering Community
+ Post

Home Posts Topics Members FAQ

Help Please: Finding out the Iterator to the Child node in binary heap

I am trying to write a generic heapsort (of course as a self-exercise)
with Iterator interface: something like blow....

But I got into trouble finding out the Iterator to the Child node. If
indexing was used, I could do something like child = hole * 2 + 1; but
since only thing the function accepts are random access Iterators, how
do I calculate the Iterator to the child node?

template <typename Iterator, typename Functor>
void heapsort(Iterat or begin, Iterator end, Functor cmp)
// I assume that begin and end are random access iterators
int noleafOffset = (end -1 - begin) / 2;
// since end is the iterator to one past the last one

for (Iterator i = begin + noleafOffset; i >= begin; i--)
shiftdown(i, end-1, cmp);
for (Iterator j = end - 1; j > begin; j--) {
swap (*begin, *j);
shiftdown(begin , j, cmp);

The problem is making "shiftdown" function template work with

template <typename Iterator, typename Functor>
void shiftdown(Itera tor top, Iterator bottom, Functor cmp)
Iterator hole = top;
----->> Iterator child = hole * 2 + 1; // This is the problem!
// I know I cannot apply operator*() to an Iterator so how do I
find an
// Iterator to the left child?

while ( bottom >= child) {
if (child != bottom && cmp( *(child + 1), *child) )
if ( cmp( *child, *bottom)) {
*hole = *child;
hold = child;
----->> child = hole * 2 + 1;
// Again, how do we find out the Iterator to child?
else break;
*hole = *bottom;

template <typename T>
void swap(T & a, T & b)
T temp = a;
a = b;
b = temp;

Can I not implement the generic heapsort template accepting only
iterators to first element and one past the last element? Please help.
Thank you in advance. BTW, I could write bubblesort, quicksort based
on this interface. I think the problem is my lack of understanding
certain features, logic, etc... I would very much appreciate any
Jul 22 '05 #1
0 1388

This thread has been closed and replies have been disabled. Please start a new discussion.

Similar topics

by: Nick Chan | last post by:
hello i have implemented joe celko's model to store heirarchy and it works well and nice i have a question about SQL this is the actual table member side left right ------------------------------------------
by: James Aguilar | last post by:
Suppose I have a class Heap that represents a binary heap in an array. Then suppose that I have another class called Heap::iterator that moves down the heap to the left or the right. Here is the code from the header file describing these two types: --- CODE --- class Heap { std::vector<int> m_vec;
by: forester | last post by:
lets say its common situation when object have subobjects in container and receives callbacks from contained items. and object want to move objects in containers on signal(callback). iterator is needed for container modifications, item cannot know its iterator, at least its not easy to do so and i think cannot be done type-safe avoiding virtual functions and stuff. 'this' pointer from items is a freeby :>. the problem is, std...
by: Tarique Jawed | last post by:
Alright I needed some help regarding a removal of a binary search tree. Yes its for a class, and yes I have tried working on it on my own, so no patronizing please. I have most of the code working, even the removal, I just don't know how to keep track of the parent, so that I can set its child to the child of the node to be removed. IE - if I had C / \ B D
by: David Hirschfield | last post by:
I've written a tree-like data structure that stores arbitrary python objects. The objective was for the tree structure to allow any number of children per node, and any number of root nodes...and for it to be speedy for trees with thousands of nodes. At its core, the structure is just a list of lists arranged so that if node A has children B and C and node B has child D the data looks like: A = B =
by: genestarwing | last post by:
QUESTION: Write a program that opens and read a text file and records how many times each word occurs in the file. Use a binary search tree modified to store both a word and the number of times it occurs. After the program has read the file, it should offer a menu with three choices. the first is to list all the words along with the number of occurences. The second is to let you enter a word, with the program reporting how many times the...
by: skrebbel | last post by:
Is there any faster/easier way of finding a child node of a certain DOMNode object than doing something like function getChildByTagname($curnode, $name) { foreach($curnode->childNodes as $node) { if($node->nodeName==$name) { return $node;
by: ryanoasis | last post by:
Working on a C++ assignment and I cant figure out the problems I am having w/ Templates and Subclasses. I know there are issues with templates and certain compilers so I am not sure what the problem is exactly. I am hoping its an easy overlook. This class is of the linkedLIst, Iterator, and Node modified to use Templates and so that Iterator and Node are subclasses of List
by: slizorn | last post by:
hi guys, i need to make a tree traversal algorithm that would help me search the tree.. creating a method to search a tree to find the position of node and to return its pointer value basically i need to read in a text file... shown below H H,E,L E,B,F B,A,C A,null,null
by: Hystou | last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it. First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
by: Oralloy | last post by:
Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed. This is as boiled down as I can make it. Here is my compilation command: g++-12 -std=c++20 -Wnarrowing bit_field.cpp Here is the code in...
by: jinu1996 | last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth. The Art of Business Website Design Your website is...
by: Hystou | last post by:
Overview: Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
by: agi2029 | last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own.... Now, this would greatly impact the work of software developers. The idea...
by: isladogs | last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome a new presenter, Adolph Dupré who will be discussing some powerful techniques for using class modules. He will explain when you may want to use classes instead of User Defined Types (UDT). For example, to manage the data in unbound forms. Adolph will...
by: conductexam | last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one. At the time of converting from word file to html my equations which are in the word document file was convert into image. Globals.ThisAddIn.Application.ActiveDocument.Select();...
by: adsilva | last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
by: bsmnconsultancy | last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.