Implementing a scheduling algorithm (assignment) [closed] - c++

Question

Closed. This question needs debugging details. It is not currently accepting answers.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
Closed 7 years ago.
Improve this question
So I am on my 2nd year of computer science and I am struggling with a part of one of my assignments.
Basically, we had to make a stack, a queue and a scheduling algorithm.
I've made the stack and queue part which will technically give me a pass, but I would like to do the remaining part as well just to be sure.
We're allowed to use ONLY iostream library, nothing else.
These are the .h files provided by our teacher:
http://pastebin.com/TcBzULZj
We HAVE to use these.
I am struggling with the algorithm as it is supposed to be a subclass of queue, using an integer for priority and storing integer values to represent process IDs.
How should I approach that?
I am not asking you to do my homework for me or anything like that, I just want to tips and a little push in the right direction :)
############################################
EDIT
I tried to do it this way:
http://pastebin.com/mFchEc6T
It does compile and start, but as soon as I try to do anything in the program it gives some memory error and turns off my program.
I guess there's something wrong with the pointers but I dont know what.
Basically the idea behind that function was to go through all the nodes from the top of the queue and compare their priority to the priority of "temp" node.
It would swap places with nodes as long as "temp" had higher priority than them (green on picture) and as soon as it hit a node with the same priority (blue) it would stop there and wait for its turn, before nodes with higher priority (red) are done.
I bet these pointers are messed up but I just can't get my head around it for life, even though I struggled with this for like 2 days already.

Answer 1

You can adding a new value with priority P after all values with priorities higher than P.
Pop values from the beginning of the list.
For example:
If you have values 1, 2, 3, 4, 5 with priorities 99, 54, 111, 27, 978
In list you have: 5(978), 3(111), 1(99), 2(54), 4(27).
If you need add value 6 with priority 105, you add it after value 3 with priority 111.

Answer 2

Look at the simple example of queue with priorities.
#include <iostream>
class Queue {
public:
Queue() :
queue( 0 )
{
}
void Push( int value, int priority = 0 );
bool Pop( int& value );
private:
struct Node {
Node* Next;
int Value;
int Priority;
Node( int value, int priority ) :
Next( 0 ),
Value( value ),
Priority( priority )
{
}
};
Node* queue;
Queue( const Queue& );
Queue& operator=( const Queue& );
};
void Queue::Push( int value, int priority)
{
Node* node = new Node( value, priority );
if( queue == 0 || queue->Priority < node->Priority ) {
node->Next = queue;
queue = node;
} else {
Node* i = queue;
while( i->Next != 0 && node->Priority <= i->Next->Priority ) {
i = i->Next;
}
node->Next = i->Next;
i->Next = node;
}
}
bool Queue::Pop( int& value )
{
if( queue == 0 ) {
return false;
}
value = queue->Value;
Node* tmp = queue;
queue = queue->Next;
delete tmp;
return true;
}
int main( int argc, const char* argv[] )
{
Queue queue;
queue.Push( 3, 100 );
queue.Push( 2, 200 );
queue.Push( 1, 500 );
int x;
while( queue.Pop( x ) ) {
std::cout << x << std::endl;
}
return 0;
}