Dynamically Linked Queues

Steve Paks

Dynamically Linked Queues

• Linked Queue

int MAX_QUEUES 10; /* maximum number of stacks */

Class Queue{

element item;

Queue link;

}

Queue front[MAX_QUEUES], rear[MAX_QUEUES];

Dynamically Linked

Queues(Cont’d)• Add to the rear of a linked queue

void addq(Element item){

Queue temp = new Queue();

if(IS_FULL(temp)){

print(“The memory is full”);

exit(1);

}

temp.item = item;

temp.link = null;

if(front != null) {

rear.link = temp;

} else {

front = temp;

}

rear = temp;

}

∙∙∙∙ (a)

∙∙∙∙ (b)

Dynamically Linked

Queues(Cont’d)• Add to the rear of a linked queue(Cont’d)

front

item

rear(=temp)

(a)

item(b)

front(=rear=temp)

Dynamically Linked

Queues(Cont’d)• delete from the rear of a linked queue

Element deleteq(){

Queue temp = front;

Element item;

if(IS_EMPTY(front)){

print(“The queue is empty?”);

exit(1);

}

item = temp.item;

front = temp.link;

return item;

}

∙∙∙∙ (a)

∙∙∙∙ (b)

∙∙∙∙ (c)

Dynamically Linked

Queues(Cont’d)• delete from the rear of a linked queue(Cont’d)

front(=temp) rear

(a)

(b) a

front rear

item

a

(c) a

front(=temp.link) rear