Implement Priority Queue using Heap C Programming.
#include<stdio.h> #include<malloc.h> void insert();
void del(); void display();
struct node
{
int priority; int info;
struct node *next;
}*start=NULL,*q,*temp,*new;
typedef struct node N; int main()
{
int ch;
clrscr(); do
{
printf("\n[1] INSERTION\t[2] DELETION\t[3] DISPLAY [4] EXIT\t:");
scanf("%d",&ch); switch(ch)
{
case 1:insert(); break;
case 2:del(); break;
case 3:display(); break;
case 4: break;
}
}
while(ch<4);
}
void insert()
{
int item,itprio; new=(N*)malloc(sizeof(N));
printf("ENTER THE ELT.TO BE INSERTED :\t");
scanf("%d",&item);
printf("ENTER ITS PRIORITY :\t");
scanf("%d",&itprio); new->info=item; new->priority=itprio; new->next=NULL; if(start==NULL )
{
//new->next=start; start=new;
}
else if(start!=NULL&&itprio<=start->priority)
{ new->next=start; start=new;
}
else
{
q=start;
while(q->next != NULL && q->next->priority<=itprio)
{q=q->next;}
new->next=q->next; q->next=new;
}
}
void del()
{
if(start==NULL)
{
printf("\nQUEUE UNDERFLOW\n");
}
else
{
new=start;
printf("\nDELETED ITEM IS %d\n",new->info); start=start->next;
//free(start);
}
}
void display()
{
temp=start; if(start==NULL)
printf("QUEUE IS EMPTY\n"); else
{
printf("QUEUE IS:\n"); if(temp!=NULL)
for(temp=start;temp!=NULL;temp=temp->next)
{
printf("\n%d priority =%d\n",temp->info,temp->priority);
//temp=temp->next;
}
}
}
