Objective : Implement a priority queue Extra Credits: Solve the starvation probl
ID: 3776459 • Letter: O
Question
Objective : Implement a priority queue
Extra Credits: Solve the starvation problem using any simple, suitable technique
Language to be used C++ (please leave comments for each syntax line)
1) Write a queue class using linked list to implement the queue. Do not us the link list from STL. The queue class should be a template class and must implement enqueue and dequeue operations. It should also have a getQLength() function that returns the number of elements in the queue.
2) Write a PriQueue class that uses the queue class. The PriQueue is also a template class. It should take a parameter "levels" as input to specify the number of priority levels. The constructor should create a vector "pq" of size "levels" to create the various priority levels. pq should be a private variable. It should overload the enqueue operation from Queue class: void enqueue(T obj, int level). It allows you to specify the priority level of the object "obj" so that you can place the object in the right queue. By default, the enqueue operation puts the object in queue 0 (lowest priority). Therefore, the function void enqueue(T obj) should place the object in queue pq[0]. The dequeue operation needs to check the queues in the order of priority. The higher levels need to be served before the lower ones. As long as there is something in the higher queue, the lower queue cannot be served. (Note that there are other ways to implement priority but we are sticking to this rule).
3) The PriQueue should implement a function void increaseLevel() that adds another priority level by inserting another level in the vector "pq". For example:
Queue q;
pq.pushback(q).
4) Test your implementation using a driver program. You should try enqueuing and dequeuing at various levels and submit the ouput along wth the code.
Explanation / Answer
This is the program i have done so far and please do let me know if any errors occur
class Queue
{
int a[100];
int rear
int front;
public:
Queue()
{
rear = front = -1;
}
void enqueue(int x); //declaring enqueue, dequeue and display functions
int dequeue();
void display();
}
void Queue :: enqueue(int x)
{
if( rear = SIZE-1)
{
cout << "Queue is full";
}
else
{
a[++rear] = x;
}
}
int queue :: dequeue()
{
return a[++front]; //following approach [B], explained above
}
void queue :: display()
{
int i;
for( i = front; i <= rear; i++)
{
cout << a[i];
}
}
return a[0]; //returning first element
for (i = 0; i < tail-1; i++) //shifting all other elements
{
a[i]= a[i+1];
tail--;
}
#include <iostream>
#include <string>
#include <vector>
using namespace std;
template <class T1, class T2>
class PriQueue
{
public:
void enqueue(T1 str, T2 pri);
void dequeue(T1 str, T2 pri);
void peek(T1 str, T2 pri); //Prints the the first in queue
void size(T1 size); //Prints how many in queue
T1 printQ();
private:
T1 s;
T2 p;
};
template <class T1, class T2>
void PriQueue<T1, T2>::enqueue(T1 str, T2 pri)
queue
{
this->s = str;
this->p = pri;
}
template <class T1, class T2>
void PriQueue<T1, T2>::dequeue(T1 str, T2 pri)
{
}
template <class T1, class T2>
void PriQueue<T1, T2>::peek(T1 str, T2 pri)
{
}
template <class T1, class T2>
void PriQueue<T1, T2>::size(T1 size) //Returning the number of items in the queue.
{
}
using namespace std;
int main()
{
PriQueue<string, int> que;
que.enqueue("Hello", 3);
que.enqueue("Bye", 2);
que.enqueue("No", 5);
cout << que.printQ() << endl;
return 0;
}
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