What is Queue: Definition and 32 Discussions

In computer science, a priority queue is an abstract data type similar to a regular queue or stack data structure in which each element additionally has a "priority" associated with it. In a priority queue, an element with high priority is served before an element with low priority. In some implementations, if two elements have the same priority, they are served according to the order in which they were enqueued, while in other implementations, ordering of elements with the same priority is undefined.
While priority queues are often implemented with heaps, they are conceptually distinct from heaps. A priority queue is a concept like "a list" or "a map"; just as a list can be implemented with a linked list or an array, a priority queue can be implemented with a heap or a variety of other methods such as an unordered array.

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  1. J

    A discrete-time queue Markov Chain problem

    The following problem is seriously tricky and I urgently need help with it, thanks. For part a: we have the following transition probability matrix P = a0 a1 a2 a3 a0 a1 a2 a3 0 a0 a1 b2 0 0 a0 b1 Now, is a0 = a1 = a2 = a3 =...
  2. chwala

    Permutation problem: Seven friends queue up for a buffet....

  3. P

    Jupiter's Gravity: How Many Ships in the Queue?

    Imagine you are in the universe of the Expanse book. First of all, you want to speed up your spaceship to reach the alien gate. And you will use Jupiter's gravity. But there is a queue of spaceship wanting to go to the gate, and they all use Jupiter's gravity to accelerate. Suddenly Jupiter...
  4. I

    Learning Data Structures in Java: Circular Queue

    Summary:: I have recently started with data structures in java and I tried doing this Program .But I have few confusions. 1.How do I write the main() of the program? 2.What are we supposed to do with the value returned by function pop()? If anyone could point out if there are any errors and...
  5. J

    Comp Sci Modeling the queues at a college restaurant

    So far, I have implemented the code below, using Java Priority Queues and Maps. I tried to identify each customer by the time they came in (ranging from 360 and onwards) and their grades. However, this is my first time using priority queues and maps, and I am not very sure if I'm doing things...
  6. E

    About the strategy of reducing the total suffering in a queue

    This is my funny theory (may be I have found already known things...).Let us assume the following abstract situation. We have a special place where people can get some kind of service (for instance any bureaucratic office). There is only one service clerk who spend a fixed time (we will call it...
  7. Mehmood_Yasir

    A Waiting time in a Queue using Poisson arrival

    Dear colleagues. I have a difficulty in calculating waiting time of the first packet arriving in a buffer using aggregation. Arrival follow Poisson process with rate lambda and the aggregation is done for a maximum 'm' packets or with the expiry of timer T_maximum. Can anyone help me how to...
  8. mertcan

    I M/G/C Queue Theory: Proving Results & Finding Sources

    hi, initially when I saw these statements , I got really amazed, and now I endeavor to find the proofs of these statements, bu I would like assure you of the fact that there are very very very few sources which evaluate M/G/K or M/G/infinite queue, mostly sources prefer to handle the subject of...
  9. G

    Data structures and algorithms: Priority queue as Binary Tree

    Homework Statement Explain and compare two efficient implementations of a priority queue using binary tree. Ilustrate this on an example of ascending priority queue that is created when elements 15, 38, 45, 21, 8, 55,20 are inserted and the two largest elements are deleted. Homework Equations...
  10. M

    Is Discarding the Higher Random Number in a Stochastic Queue Simulation Correct?

    Hello guys! I am learning a bit on queue theory in one of my courses, and decided to try and do some simulations even though it is not mandatory. (Curriculum only covers the steady state, where it can be treated mathematically with ease). Im looking at a birth-death process, where the time til...
  11. J

    MHB Double ended queue data abstraction.

    Hi, I'm working through a question where I need to design the Deque data abstraction giving it's formal specification with axioms. A deque is a queue where items can be added to and remove from either end of the queue. I've already got an abstraction for a normal queue and from what I can see...
  12. O

    Real life queue - how to model?

    People queuing to pick up photos at an event. They have a bar-coded docket. By scanning the docket, printing is initiated on one of eight printers. Each printer takes 40 seconds to print a photo - the software chooses the least heavily loaded print queue - or uses a round-robin approach if print...
  13. evinda

    MHB Exploring Static Queue Operations and Complexity

    Hi! (Wave) I am looking at the operations of a static queue. pointer MakeEmptyQueue(void) pointer Q; /* temporary pointer */ Q = NewCell(Queue); /* malloc() */ Q->Front = 0; Q->Length = 0; return Q; I have to find the complexity of the above...
  14. B

    Analysis of Billiards Ball Motion Following a Horizontal Queue Impact

    [b]1. Encountered with cue to a massive billiards ball, which is initially at rest, see figure uploaded. The ball has radius R and mass M. The queue hits with force F horizontally into the bale height h above the table, and the shock lasts a very short time Δt. It is reported that the moment of...
  15. S

    Finding Core Number On Queue and LSF

    I’m trying to find out the largest number of cores that can be used on a specific queue in LSF with the bqueues command. I’ve used the option –l after reading the manual, but I don’t see any information about cores listed. Any suggestions? Thanks.
  16. C

    Statistics Queue problem: M/M/2

    Homework Statement OK I am dealing with a Queue type problem that is M/M/2. I have already solved most of the problem but I can not figure out how to solve for ∏0, Lq, L, & W. The information I am given is: λ=11.98, μ=7 and s=2. Homework Equations The Attempt at a Solution I am...
  17. L

    M/M/1 Queue System: Calculating A, B, C

    Homework Statement For an M/M/1 queuing system with the average arrival rate of 0.4 min^−1 and the average service time of 2 minutes, compute A- the expected response time in minutes; B- the fraction of time when there are more than 5 jobs in the system; C- the fraction of customers who...
  18. D

    How to creaate a priority queue using print queue

    Homework Statement Its a lot but here is the assignment: You are going to implement an event driven simulation of a priority queue serving a printer. Each job will have one of 5 priorities: enum Priority { development, client, preferred, highest, scheduled }; The printer will be assumed...
  19. M

    Optimizing a parallel queue

    Homework Statement You want to process x units of a product (at y processing plants), minimizing the total time spent processing all the units. Each place y_i has a queue of q_i units ahead of you and a processing rate of r_i units/minute. If you can simultaneously process units at the same...
  20. S

    Queue is i am in the right trick

    Ernie is always keen to go to the Family on Saturday nights and usually arrives around 11pm. On a particular night, Bert decides to start drinking early and he is already inside the Family while Ernie is on his way. Ernie has noticed over time that the expected number of people in the queue to...
  21. M

    Stochastic processes: infinite server queue with batch poisson arrivals

    Hi everyone, I am trying to solve this problem but I am stuck with doubts. Here are my ideas. Homework Statement Busloads of customers arrive at an infinite server queue at a Poisson rate λ Let G denote the service distribution. A bus contains j customers with probability aj = 1...
  22. J

    C/C++ Queue made with pointers in C++, questions

    Can someone explain how the function queue::store(int i) (see attachment) works for a sequence of calls to it. Or give a reference to something or give a diagram, please. Doesn't each instant (i.e., each memory location) have its own head, tail and next pointers as well as as the data member...
  23. A

    Queuing Theory problem, M/M/1/K queue with twist

    Homework Statement Customers arrive to a register as a poisson process with arrival rate λ and are serviced with an exponential distribution with service rate μ. When a customer arrives he'll decide to join the line or not depending on how many people are currently in the system (not including...
  24. A

    Queuing Theory problem (M/M queue)

    Homework Statement Given an M/M type queuing model on an first come first save basis, where 2 kinds of customers (type 1 and type 2) arrive as poisson processes with arrival rate λ1 and λ2 respectively, being served by one cashier with timewise exponential distribution with parameter μ...
  25. 0

    Checking if a circular queue is full

    So, my teacher comes to the lecture, writes the notes on the board... and then says: "from now on this part is intuitive"... he means this part: (myFront != (myBack + 1) % max) of the following (C++) code:- void Queue::addQ (int x) { if (myFront != (myBack + 1) % max) { ...
  26. M

    Passengers entering a queue

    Hi, I am trying to assign a distribution to the the rate at which passengers enter a queue over a period of time. The period of time is to remain constant. Passengers start arriving 4 hours before a flight and stop arriving at the scheduled time of departure. I have been using a Weibull...
  27. S

    News Why wouldn't the LHC break on queue?

    Just watching the live feed from the LHC and as if the black hole it was meant to create was speaking to us, it broke on queue. Seriously..is this thing not the biggest piece of junk ever invented? Obviously it is complicated beyond the scope of this forum..but with scientists studying it for...
  28. A

    Solving: Why Destroying a Queue Doesn't Work

    Homework Statement All I need is an explanation as to why the algorithm I've been given doesn't destroy the queue properly. When I use the code below, and I check if q is NULL or not, it says it isn't, and I'd like to know why. Thanks :)Homework Equations None, this is computer science...
  29. S

    Can You Improve the Time Complexity of Building a Queue with Stacks?

    Hello, I'm tasked with building a queue from as many stacks as I'd like, trying to get the fastest implementation possible. The best I can think of is using two stacks and as you enqueue items you push them on the first stack stack, but every time you want to dequeue if there are n items...
  30. L

    Angle of Queue Ball after elastic collision

    Homework Statement Assume an elastic collision (ignoring friction and rotational motion). A queue ball initially moving at 2.2 m/s strikes a stationary eight ball of the same size and mass. After the collision, the queue ball's final speed is 0.61 m/s. Find the queue ball's angle \theta...
  31. S

    Having Trouble with 'D' Option in Stack and Queue ADT Program?

    Hello everyone, I have been trying to figure this problem since hrs, please help me out. It is most likey very easy for you people. I think the problem is mostly syntax but here it is. I am writing this program which uses Stack and Queue ADT . If you look at the code the program is...
  32. E

    What is the distribution of service in a M/M/1 airport simulation queue?

    I hope this is the right 'subforum' to post my question, if not, sorry, I was not sure... What kind of model is airport simulation of a queue (planes land and take off) with one runway (one server only). I am sure about the first and the last parameter but not about the 'middle': M/(const)/1...
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