# Recent questions tagged queue

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Which of the following is useful in traversing a given graph by breadth first search? Stack Set List Queue
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If queue is implemented using arrays, what would be the worst run time complexity of queue and dequeue operations? $O(n),O(n)$ $O(n),O(1)$ $O(1),O(n)$ $O(1),O(1)$
1 vote
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A ________ is a linear list in which insertions and deletions are made to from either end of the structure. Circular queue. Priority queue. Stack. Dequeue.
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A queue is implemented using an array such that ENQUEUE and DEQUEUE operations are performed efficiently. Which one of the following statements is CORRECT($n$ refers to the number of items in the queue)? Both operations can be performed in $O(1)$ time. At most one ... complexity for both operations will be $\Omega(n)$. Worst case time complexity for both operations will be $\Omega(\log n)$.
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A First In First Out queue is a data structure supporting the operation Enque, Deque, Print, Enque(x) adds the item $x$ to the tail of the queue. Deque removes the element at the head of the queue and returns its value. Print prints the head of the queue. You ... in reverse order. If the queue had $n$ elements to begin with, how many statements would you need to print the queue in reverse order?
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Show how to implement a queue using two stacks. Analyze the running time of the queue operations.
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Whereas a stack allows insertion and deletion of elements at only one end, and a queue allows insertion at one end and deletion at the other end, a deque (double ended queue) allows insertion and deletion at both ends. Write four $O(1)$ time procedures to insert elements into and delete elements from both ends of a deque implemented by an array.
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Rewrite ENQUEUE and DEQUEUE to detect underflow and overflow of a queue.
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ENQUEUE(Q, x) 1 Q[Q.tail] = x 2 if Q.tail == Q.length 3 Q.tail = 1 4 else Q.tail = Q.tail + 1 DEQUEUE(Q) 1 x = Q[Q.head] 2 if Q.head == Q.length 3 Q.head = 1 4 else Q.head = Q.head + 1 5 return x illustrate the result of each operation in the sequence ENQUEUE(Q,4),ENQUEUE(Q,1),ENQUEUE(Q,3),DEQUEUE(Q),ENQUEUE(Q,8),DEQUEUE(Q) on an initially empty queue $Q$ stored in array $Q[1...6]$.
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I'm learning data structures from a book. In the topic, Circular Queue using Dynamic Array, the author has mentioned below point, Let capacity be the initial capacity of the circular queue,We must first increase the size of the array using realloc,this will copy maximum ... copies at most capacity elements. But how does array doubling and slide to right copy at most 2 * capacity -2 elements??
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A circular queue has been implemented using a singly linked list where each node consists of a value and a single pointer pointing to the next node. We maintain exactly two external pointers FRONT and REAR pointing to the front node and the rear node of the queue, respectively. ... rear node to front. We dont need to do this. So why B is the correct answer?D should be correct ? please explain.
1 vote
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5. Assume I have a stack s, a queue q, and a binary search tree t. Initially all of them are empty. Indicate the state of the data structures at line number 7 and at the end. What is the maximum height each of the data structures had during the execution? 1 i $\rightarrow$ 0 2 while i <= ... $\rightarrow$ 0 8 while i <= 9 do 9 t.insert(s.pop()) 10 t.insert(q.get()) 11 i $\rightarrow$ i + 1 12 end
1 vote
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true/false ? ) if stack is implemented as a array,all operation push ,pop ,is emptystack(),delete stack() can be performed in constant time. )if stack is implemented as a linked list ,all operation ,is emptystack(),delete stack() can be performed in constant time.
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The array implementation of Queue throws an error when the array limit has been reached. So we consider the following alternative. Create a larger array using redefine function. The cost of the redefine that makes the array larger is proportional to the new size. Suppose we expand the array capacity by one ... of $N$ insertions will take. $O(N^2)$ $O(N^3)$ $O(N)$ $O(log_2N)$ Answer provided: $A$
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Is priority queue work efficiently with sorted array than unsorted array and heap for insertion and deletion operation? Then why do we apply priority queue in heap specially
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____ number of queues are needed to implement a stack $1$ $2$ $3$ $4$
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WHAT IS THE TIME COMPLEXITY TO ENQUEUE AN ELEMENT IF THE QUEUE IS IMPLEMENTED AS A CIRCULAR QUEUE AND WE HAVE GOT ONLY ONE POINTER TO FRONT ELEMENT??
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1) How many stacks are needed to implement a queue . 2) How many queue are needed to implement a stack.
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https://gateoverflow.in/?qa=blob&qa_blobid=11435838562783483664 Approach for Q9 please . (Please note: it is the last question on left hand side, and part of it is written on right hand side) Answer is d, but according to me it should be b as in 3 situation when C is a ... Of elements but won't be restored in it's original state as mentioned in question. So only 1 and 2 is possible. Is it correct?
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https://gateoverflow.in/?qa=blob&qa_blobid=10936115150698131975
1 vote
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What are the minimum number of pointers required to implement a stack using single ended queue ( the queue is NOT a dequeue )?
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On other sources, it is given that we need to assign high priorities to newly inserted element in case of stack otherwise low priority to newly inserted element in case of queue. My doubt here is that shouldn't stack be implemented with max-heap priority queue and queue with min-heap priority queue keeping above assumption of assigning priorities to newly inserted element?
1 vote
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In implementation of queue using stack, deletion of second element from front take Ο(n) time, when insertion take Ο(1) time. Is it a true statement ? Well it can be true isn't it ? because suppose elements come we simply push them without taking care of the order in ... everything back to stack1. dnQueue(q) 1) If stack1 is empty then error 2) Pop an item from stack1 and return it Am i right?
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Its GATE 2013 question Consider the following operation along with Enqueue and Dequeue operations on queues, where k is a global parameter. MultiDequeue(Q){ m = k while (Q is not empty) and (m > 0) { Dequeue(Q) m = m - 1 } } What is the worst case time complexity of a sequence ... are performed on non-empty or full queue?? Due to this change will the answer remain same?? Θ(n) Θ(n + k) Θ(nk) Θ(n2)
1 vote
Consider implementation of stack using queue by following algorithm. Let $x$ be an element to be pushed in the stack push(q1,x) { EQ(q1,x) while(q1 does not contain 1 element) { k=DQ(q1) EQ(q1,k) } } pop(q1) { DQ(q1) } How many enqueue and dequeue operations required to push $2$ and pop $2$ elements in the empty stack?
A queue is implemented using a non-circular singly linked list. The queue has a head pointer and a tail pointer, as shown in the figure. Let $n$ denote the number of nodes in the queue. Let 'enqueue' be implemented by inserting a new node at the head, and 'dequeue' be implemented by deletion of a ... ? $\Theta(1), \Theta(1)$ $\Theta(1), \Theta(n)$ $\Theta(n), \Theta(1)$ $\Theta(n), \Theta(n)$