In this type of queue, elements are associated with priorities and execute according to priority. If there are two same priorities, then they will be executed according to the value associated with the priority.
Priority queue applications are used when balancing the load in Operating systems, in Dijkstra’s algorithm, etc.
In queues the first element will be removed first. Here it is based on higher priority
Rear - Gets the last item from queue.
Front - Gets the first item from queue.
Size - returns the length of the queue.
append()for enqueue and
def element(a): return a pqueue = [(1,34),(2,21),(5,11),(3,39),(5,35),(1,36)] #(priority,value) def deletinghighestpriority(x): a = sorted(pqueue,key=element) m = max(a) pqueue.remove(m) return pqueue print("front of the queue = ",pqueue) print("rear of the queue = ",pqueue[-1]) print("deleted highest priority queue=",deletinghighestpriority(pqueue))
The double ended queue is under a linear data structure where both ends of the queue can be used for insertion and deletion.
It is used as a stack as well as a queue, where
both ends are used for insertion and
append() - adds element to right end.
appendleft() - adds element to left end.
insert(index,value) - adds at given position.
extend(list) - adds multiple elements to right end.
extendleft(list) - adds multiple elements to left end.
pop() - removes element from right end.
popleft() - removes element from left end.
remove(value) - deletes first occurrence of value.
count(value) - returns number of occurrences of that value.
index(e,start,end) - searches index of ‘e’ from given start to end.
reverse() - prints the elements in reverse order.
import collections de = collections.deque([1,25,3,34,2,25]) print("The deque after after deleteing the element:") de.remove(3) print(de) de.extend([1,2,3]) print("New deque extend right=",de) de.extendleft([1,2,3]) print("New deque extend left=",de) de.popleft() print("New deque left deletion=",de) de.append(100) print("New deque add right=",de)
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