I know queue but with priority queue i am really amateur. How to implement some functions in priority queue.
template <class T> class PRIORITY_QUEUE {
private:
T *items; // array of queue items
int rear;
int maxSize; // maximum size of queue
[Code] ....
and what does heapify mean???
How to build a FiFO queue without using the STL (done that no problem), get it to dequeue (again, done that no problem). However, to get those extra marks, I need to be able to order it using a priority system.
I've tried ordering the NodeDequeue class that I'll show at the bottom of this post, but I just cannot get it to order appropriately. The closest I have got is everything in order but I lose a Node from the memory completely. So, that's no good.
The most logical idea I have thought of right now is to send the largest number to the back of the queue each time it's iterated, eventually, the largest number will end up at the front.
class PriorityQueue : public Queue {
public:
Node* NodeDequeue(void) {
Node* tmp = front;
Node* seek = tmp->getPrev();
[Code] .....
I'm trying to implement Prim's Algorithm and for that I need to have a decreaseKey method for a priority queue (to update the key value in a priority queue). Can I implement this in the STL Priority Queue?
This is the algorithm I'm following:
for each vertex u in graph G
set key of u to INFINITY
set parent of u to NIL
set key of source vertex to 0
en-queue to priority queue Q all vertices in graph
[Code] .....
I've got a priority queue of items who, from time to time, returns a different comparison result. Any way to re-sort a priority queue who is storing them?
Example:
#include <cstdlib>
struct Random {
bool operator<(const Random&) const { return !(rand()&1); } };
how double ended priority queue be used to implement external quick sort?
View 8 Replies View Relatedwrite a program, pfpq.c, that maintains a priority queue of music tracks (songs) and ratings. The struct is given by:
Code:
struct track
{
char artist[20];
char title[20];
int rating;
};
The program is only designed to demonstrate the concept so get the user to enter a small number of tracks and create a priority queue. (Use an empty string title or an empty string artist to end the program). Print the priority queue as it grows. Your program should initially ask the user if they wish to order the priority queue by rating in ascending order, or by rating in descending order, or if they wish to order the priority queue by artist name. Then build the priority queue accordingly. in the last case, "if they wish to order the priority queue by artist name." which is case 3. How do I sort the priority queue by artist name using in the following code.
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "pqueue.h"
struct track
{
char artist[20];
char title[20];
int rating;
}
[code]....
i am working on creating a priority queue, i seem to have done the algorithm for inserting from the top correctly but the algorithm for inserting from the bottom doesnt seem to work it just overwrites the existing data.
below is my code :
list is an array and listlength is the size of the array declared as a integer
void inserttop(string task) {
//int head = 0 ;
string temp ;
listlength++ ;
for (int i = 1; i < listlength; i++) {
[Code]...
So i have been banging my head against a wall with this problem for awhile. I have also copy and pasted direct examples from the internet but nothing seems to sort it right.
Node Header
Code:
#ifndef _NODE_H
#define _NODE_H
#include <stdio.h>
class Node {
public:
Node();
Node(int weight, char value, Node* left = NULL, Node* right = NULL);
[Code] ....
On several occasions in my project, I need to sort elements (indeces) based on their linked values. Those values are stored in an array. This means the comparison looks like this:
bool operator()(int i, int j) { return someArray[i] > someArray[j]; }
Because this form returns often but someArray may differ, I wrapped this in a template class:
template<class T>
struct sorter {
std::vector<T>& data;
sorter(std::vector<T>& __d) : data(__d) {}
bool operator()(int i, int j) const { return data[i] > data[j]; }
};
Now, I want to use this in a different way: I want to select the K indeces with the lowest value from someArray attached to it. My idea was to build a priority_queue, push the first K elements and then compare all the next elements to PQ.top(), as such:
INDEX t(0);
for (; t < someLimit; ++t) {
pq.push(t);
if (pq.size() == K) break;
}
for (; t < someLimit; ++t) {
if (someArray[t] < someArray[pq.top()]) { pq.pop(); pq.push(t); }
}
My problem, however, is the definition / initialization of the priority_queue object. My first idea was simply std::priority_queue<INDEX> pq(sorter<VALUE>(someArray));, but calling any function on pq provides the error "expression must have class type" (?) when hovering over pq.
My second guess, std::priority_queue<INDEX, std::vector<INDEX>, sorter<VALUE>(someArray)> pq;, provides the error 'expected a ')'' when hovering over someArray.
What is the correct way to initialize this data structure?
This assignment is about Heap and PQ's to sort out jobs inside a printer. I'm far from finishing the assignment but the most important part isn't working. My issue is that nothing is getting stored inside the array. I keep getting crashes and at this point I'm not sure what to do. I notice that my destructor runs right after my "addJob" Function finishes, which is destroying the memory. Which might be why nothing gets stored inside OR I think my implementation of Heap/PQ is wrong.
Functions inside my test.cpp aren't properly done, they are made just to see if something is stored inside.
1. Check if I created the array correctly [PQtype.cpp / Heap.h/ PQType.h]
2. Am I even using/storing into the array. [Test.cpp "addJob" Function]
3. I'm also new to working with Class Templates.
PQType.h
template<class ItemType>
class PQType {
public:
PQType(int);
PQType(const PQType&); /
[Code] .....
There appears to be some kind of error in by removeMin() function. Inserting items seems to work just fine but attempting to remove any items gives me the error "vector subscript out of range".
Here is my SortedPQ class... Below it you will find the quicksort implementation, in case looking at it is necessary.
template <class Type>
class SortedPQ {
private:
int front;
int rear;
vector<Type> V;
public:
SortedPQ(void) : front(-1), rear(-1), V(0){}
[Code] ....
I've got 2 classes, Store and Transaction and I would like to create a priority queue of objects Transaction as a variable of Store class.
My store.h
#ifndef __STORE_H_INCLUDED__
#define __STORE_H_INCLUDED__
#include <queue>
using namespace std;
#include "Transaction.h"
struct TransactionCompare;
[Code] ....
The error im getting with this set up is
error C2664: 'bool TransactionCompare::operator ()(const Transaction &,const Transaction &)
const' : cannot convert parameter 1 from 'Transaction *' to 'const Transaction &'
I'm trying to use a priority queue sorting in reverse order to take a vector or 2d array. The problem is that I want to sort by the vector/array cell value but keep the reference to the vector/array index of the value. I don't know quite howto keep them both related so when I pop. I can find the corresponding cell.
priority_queue<int, vector<int>, greater<int> > Open;
implementing an algebra function.(a+b)(a-b).does c++ support this sort of function.Did a quick search on google and all of them suggested using libraries like boost. is there anyway to do this without a library?
View 3 Replies View RelatedHow to implement the main queue functions Enque() and Deque() using two stacks S1 & S2. You allowed only to call push () and pop() functions of the two stacks to implement Enque()and Deque() functions.
#include<iostream>
using namespace std;
const int size=5;
int arr[size];
int front=-1,rear=-1;
bool isfull() {
if(rear==size-1)
[Code] .....
I have a paradigm in a loop of queues of a vector,if a condition is true,increase sizes of the queue of that particular queue in the loop of queues, if condition is false, the queuesize is left as such in loop of queues. After this operation i need to search the queue sizes of all queues and enqueue in the shortest queue.
I want to do something like the code given below
#include <vector>
#include <queue>
int min_index = 0;
std::vector<std::queue<int> > q
std::size_t size = q.size();
[Code] ....
How to implement this logic?
will q[i].size=q[i].size+5 increase the queuesize by 5 for the ith queue?
Is it possible to write a program such that it will automatically execute the function in queue base on their priority even if user programmed it randomly?
Code:
function1(){ very_important; }
function2(){ important; }
function3(){ less_important; }
int main() { // Programmed by user
function3;
function1;
function2;
//Output: Program will execute function1, 2 and lastly 3.
}
I have created a string array of 5 and I will use that to enter some "tasks", then I also have an integer array of 5 where i can assign priorities to the information in the string
string info[5];
int p[5];
cout<<"Enter info 1"<<endl;
cin>>info[0];
cout<<"Enter priority"<<endl;
cin>>p[0];
etc,
I want to be able to link the priorities that i assign to that string and be able to call the information that has the highest priority. I can only using iostream and string header files so far,
quishing some bugs, and also how to go about squishing these bugs?
#include "stdafx.h"
#include<stdio.h>
#include<malloc.h>
[Code].....
Here are the errors after compiling the program.
I'm the author of a realtime MIDI software called ChordEase which makes use of the MIDI aspects of the multimedia API, specifically MIDI input callbacks. In XP and before, these callbacks originated in the kernel and therefore had realtime priority by definition, but from Vista on, they originate in thread pool threads, and have a priority of zero. This is a problem because at priority zero they can be blocked by the GUI thread, causing serious latency, and I have proved that such blocking occurs.
I have experimented with raising the callback thread priority, using either of the following methods: 1) calling SetThreadPriority within the MIDI input callback function, and then setting a flag so that it isn't done repeatedly, or 2) creating a DLL that catches thread creation via DLL_ATTACH_THREAD in DllMain, and calling SetThreadPriority there. The first method is slightly wasteful since the flag has to be tested for every MIDI input event, but it also has the advantage of only affecting the MIDI input threads, whereas the second method affects all threads in the pool regardless of what they're used for. Neither method appears to cause any harmful effects but they make me nervous*. Other possible methods would include 3) using the thread pool API to raise the priority of the pool (assuming I could gain access to the pool handle somehow), or 4) permanently lowering the priority of the GUI thread, which I'm very reluctant to do because of the risk of unintended consequences.
I'm assuming the MIDI input callbacks are using threads in the default thread pool though I haven't actually proved this. Assuming that's so, are these threads private to my application, or is my application sharing them with other applications? Is there a safer way to achieve the result of increasing the priority of MIDI input callbacks? It's incredibly frustrating that MS would change the behavior of MIDI input callbacks so drastically without even telling anyone, but that's how it goes!
[URL] ....
*See for example theses warnings about changing thread pool priorities : [URL] ....
I'm trying to implement a T9 (predective text) project in c++ using k-ary Tree.
I would like to understand how can I add the words in the Tree and how can I display them later.
inside each node of the tree I have a linked list (for the words) and a vector of pointers to access the next node
Here are my structs :
struct NodeList{
string data;
NodeList * next;
};
struct List{
NodeList *head;
[code].....
I'm a little confused by my programming assignment this week. I've been working at it Wednesday and I've made progress but I'm still confused as to how I'm supposed to do this. The class I made is called Stack, and it's derived from a template class called StackADT. We also utilize a class called unorderedLinkedList, which is derived from a class called linkedList.
We're supposed to implement all of the virtual functions from stackADT in the Stack class. The Stack data is stored in a an unorderedLinkedList, so what I'm confused by is how to implement a few of the Stack functions because there are no functions in unorderedLinkedList which we could call to manipulate the data.
As you can see from my attached code, I'm really confused by how I'm supposed to implement the pop() and top() functions, and I also think my initializeList() function is wrong. We don't have any similar functions in unorderedLinkedList to call, so I'm at a loss of how i'd access my unorderedLinkedList. My initial thought was to call the similar functions in the class that unorderedLinkedList was derived from, linkedList, but I'm unsure of this is what we're supposed to do, or if theres actually a way to access my unorderedLinkedList without having to use the functions from the base class.
NOTE: We're not allowed to modify stackADT, unorderedLinkedList, and linkedList.
Stack.h
#include "stackADT.h"
#include "unorderedLinkedList.h"
template<class Type>
class Stack: public stackADT<Type>{
template <class T>
struct nodeType
{
T info;
nodeType<T> *link;
[Code]...
Today I am refining my skills on graph theory and data structures. I decided to do a small project in C++ because it's been a while since I've worked in C++. I want to make an adjacency list for a directed graph. In other words, something which looks like: 0-->1-->3 1-->2 2-->4 3--> 4-->This would be a directed graph with V0 (vertex 0) having an edge to V1 and V3, V1 having an edge to V2, and V2 having an edge to V4, like this:
V0----->V1---->V2---->V4
|
|
v
V3
I know that in order to do this, I will need to create an adjacency list in C++. An adjacency list is basically an array of linked lists. Okay, let's see some pseudo C++ code:
Code:
#include <stdio>
#include <iostream>
using namespace std;
struct graph{
[Code] ....
This pseudocode is currently far from the mark. And that is what -- pointers and structs in C++ have never been my strong suit. First of all, this takes care of the vertices that a vertex points to -- but what about the vertex itself? How can I keep track of that vertex? When I loop over the array, it will do me no good to only know what vertices are being pointed to, rather than also knowing what points to them. The first element in each list should probably be that vertex, and then the elements after that are the vertices it points to.
But then, how can I access this first element of the list in my main program?. I would like to be able to loop over this adjacency list to do some cool things with graphs. For example, to implement some graph theory algorithms (sorts, shortest paths, etc) using the adjacency list representation. (Also, I had a question about the adjacency list. What is different than just using a list of arrays? Why can't I just have a list with an array at each element in the list?)
I am an experience C programmer but never implement GUI.
I need to make a demo implementation that will be run on Linux and will implement GUI.
I searched the WEB and found lot of information, among is implementing the GUI in HTML and run the API through web browser.
How can I make such implementation in C?
Implement ksmall as a C++ function. Use the first item of the array as the pivot. This is what I have so far, but everytime I compile it crashes ....
#include <cstdlib>
#include <iostream>
using namespace std;
int kSmall(int k, int anArray[], int first, int last);
[Code] ....
i want to implement dfa that accepts the binary string with at least two 0's after every 1 .....
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