Answer to Question #273410 in C++ for zain

Question

priority Queues

modify the class queues so that it now behaves as a priority queue. A priority queue is a queue whose enqueue function is different in such a way that if a node has a priority value higher than the one already in the queue, it rearranges so that now the higher priority node is before the lower priority node in the queue.

we shall make a priority queue of a shopping list. the shopping list is defined by a dynamic collection of nodes containing itemName and isleNo. the list is prioritized according to isleNo. in any shopping mart, the isle numbers are arranged in ascending order. a mart can only have 20 isles at maximum.

Answer 1

#include <bits/stdc++.h>
using namespace std;
typedef struct node
{
	int data;
	int priority;


	struct node* next;


} Node;
Node* newNode(int d, int p)
{
	Node* temp = (Node*)malloc(sizeof(Node));
	temp->data = d;
	temp->priority = p;
	temp->next = NULL;


	return temp;
}
int peek(Node** h)
{
	return (*h)->data;
}
void pop(Node** h)
{
	Node* temp = *h;
	(*h) = (*h)->next;
	free(temp);
}
void push(Node** h, int d, int pr)
{
	Node* srt = (*h);
	Node* temp = newNode(d, pr);
	if ((*h)->priority > pr)
	{
		temp->next = *h;
		(*h) = temp;
	}
	else
		while (srt->next != NULL &&
			srt->next->priority < pr)
		{
			srt = srt->next;
		}
		temp->next = srt->next;
		srt->next = temp;
	
}


int isEmpty(Node** h)
{
	return (*h) == NULL;
}


int main()
{
	Node* p = newNode(10, 1);
	push(&p, 11, 2);
	push(&p, 12, 3);
	push(&p, 13, 0);


	while (!isEmpty(&p))
	{
		cout << " " << peek(&p);
		pop(&p);
	}
	return 0;
}