C++ :: Priority Queue - Inserting Into Bottom Of Array
Jan 24, 2013
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]...
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Feb 27, 2015
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] .....
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Aug 7, 2014
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;
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Nov 28, 2014
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] .....
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Jan 19, 2013
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] .....
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Nov 4, 2013
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); } };
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Jun 19, 2013
how double ended priority queue be used to implement external quick sort?
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Oct 28, 2014
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???
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Jan 4, 2014
write 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]....
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Jan 27, 2013
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] ....
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Aug 19, 2013
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?
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Mar 1, 2015
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] ....
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Dec 4, 2013
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 &'
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Jan 16, 2014
#include "stdio.h"
char t[16] = {0x8F,0x78, 0xC6, 0x12, 0xBA,0x98, 0xA2,0x16, 0x8F,0x78, 0xC6, 0x12, 0xBA, 0x98, 0xA2, 0x16} ;
char w[44];
void main(){
for(int i=0 ; i<4 ; i++){
w[i] = (t[4*i], t[4*i+1], t[4*i+2], t[4*i+3]);
printf("%0x ",w[i]);
}
}
i want to put some elements of the t array into the w array but when i do this, it prints only t[4*i+3]
i want the output to be something like this
w[0] = t[4*i], t[4*i+1], t[4*i+2], t[4*i+3] = 0x8F,0x78, 0xC6, 0x12
w[1] = 0xBA,0x98, 0xA2,0x16
and so on
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Jan 27, 2014
For some reason, my input seems to lag one behind when inserting data. Attached, I have code that I wrote along with the example of the lag. What may be wrong with my code that is causing this to lag?
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Nov 19, 2013
I have the structure defined in the code below and need to insert a new string into the middle of the string array. I know there is a way to insert a new element with a vector. How to do this. I have tried several variations similar to uniqueList.word.insert(400,"disisdabomb"); but with no luck.
const int maxWordCount=1500;
struct wordCountList
{
string word[maxWordCount];
int count[maxWordCount];
};
wordCountList uniqueList;
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Apr 19, 2014
Below is an extracted portion of an example exercise from the C Programming Language book:
Code:
void escape(char * s, char * t) {
int i, j;
i = j = 0;
while ( t[i] ) {
switch( t[i] ) {
[Code] ....
Here's my problem with this. s is a pointer to a char array. That means each index stores 1 byte. A backslash character '' is one byte. In above example, we escape it with a second backslash character: ''. That means we have two bytes there. So why does it allow inserting two bytes into a one byte index?
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Nov 8, 2014
I'm trying to code the program that will store item data.And I'm having problems to receive user-input string to array.
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <string>
#include <iomanip>
using namespace std;
[code].....
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Feb 20, 2013
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?
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Jan 28, 2015
So let say I got some numbers like so in a .txt file
Code:
12 13 22 22 43 45
23 54 87 89 98 88
34 55 76 88 8 88
45 32 45 28 98 88
I want to write a code to have them from bottom to top in a new .txt file and with other modifications like so..
Code:
{45, 32, 45, 28, 98, 88},
{34, 55, 76, 88, 8, 88},
{23, 54, 87, 89, 98, 88},
{12, 13, 22, 22, 43, 45},
Is there a start of file flag (sof) like eof ??? Because they are going to be passed into a 2 dimensional array and the data is a whole lot to be entering them by hand...
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Apr 28, 2014
I tried to keep the coding style as similar as possible. I tested these with 4 million (4x1024x1024) 64 bit unsigned integers, Visual Studio 2005, 64 bit mode, Win XP X64, Intel 2600K 3.4ghz cpu. The average time for top down = 3.7 seconds, bottom up = 3.5 seconds.
Code: // tsorttd.h - top down merge sort
template <class T>
T * TopDownMergeSort(T a[], T b[], size_t n) {
TopDownMergeSortAtoA(a, b, 0, n);
[Code]....
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May 3, 2013
Code:
typedef vector<int> LIST; // LIST can be a vector of any comparable type
static LIST merge_sort(LIST &linp){
size_t i, width;
LIST lout(linp.size()); // second list for output
[Code] ....
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Feb 21, 2014
Is it possible to display a message at the bottom of a dialog box shown in the attachment? If so, how?
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Jun 28, 2013
/* Implementation of a circular queue of Array containg names.. */
# include <stdio.h>
# include <conio.h>
# include <stdlib.h>
# include <string.h>
# define QSIZE 5
typedef struct{
[Code] ....
I changed my code. but whenever i typed in the ILoveBacolod it takes it as a whole, and if i deleted it deletes the string not the letter. for example:
Enter String: ILoveBacolod
Enter a command: Delete (D)
Output: LoveBacolod
Enter a command: Delete (D)
Output: oveBacolod
Enter a command: Add (A)
Enter a character: z
Output: oveBacolodz
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Mar 26, 2013
I have an assignment where i am required to code up in C, a program to simulate a taxi rank that is implemented as a queue via an array that can hold up to a maximum of six taxis.When a taxi arrives, it joins the rear of the queue. When a taxi departs, the first taxi in the rank is used and its departure is logged.A "rolling menu" comprising integer codes as specified below is used until 0 is entered to exit the simulation. I've done this stage but now the next stage is asking me to implement the queue as a linked list. what the difference is between an array and a linked list and what is a linked list?
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Mar 14, 2013
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.
}
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