miniQueue

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CSE 331 Lecture 12 Queue Implementations
Simulation
miniQueue() class API member
functions Bounded Queue circular
nature indexing class API member
fuctions Simulation Time driven Drive up
tellers Traffic intersection
Review Topics to date Projects
Proposed Texas Hold-Em Twixt Client/Server
Music Player Football Depth Charting ollehtO
Jeopardy Jigsaw Puzzles Texas Hold-Em AIM Bot
Creator
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(No Transcript)
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miniQueue d_queue.h

• template
• class miniQueue
• public
• miniQueue() // create an empty queue
• void push(const T item) // append item to
  queue
• void pop() // remove item from front of
  queue
• T front() // return reference to front
  queue item
• const T front() const // const version of
  front()
• int size() const // return queue size
• bool empty() const // is the queue empty?
• private
• list qlist // maintain queue items
  and size

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miniQueue d_queue.h

• template
• miniQueueminiQueue()
• // append item to back of queue
• template
• void miniQueuepush(const T item)
• qlist.push_back(item)
• // remove the item from front queue
• template
• void miniQueuepop()
• if (qlist.size() 0)
• throw underflowError("miniQueue pop()
  empty q")
• qlist.pop_front()

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miniQueue d_queue.h

• // return reference to front item in queue
• template
• T miniQueuefront()
• if (qlist.size() 0)
• throw underflowError("miniQueue front()
  empty q")
• return qlist.front()
• // return const reference to front item in queue
• template
• const T miniQueuefront() const
• // if queue is empty, throw underflowError
• if (qlist.size() 0)
• throw underflowError("miniQueue front()
  empty q")
• return qlist.front()

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miniQueue d_queue.h

• // return the queue size
• template
• int miniQueuesize() const
• return qlist.size()
• // is the queue empty?
• template
• bool miniQueueempty() const
• return qlist.empty()

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The Bounded queue
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Indexing into circular array

• Incrementing of indices wraps-around to
  beginning
• Method using a count of queue items items in
  range front .. back)
• Initially, count 0, front 0, back 0
• Queue is full if count MAXQSIZE
• Queue is empty if count 0
• To pop, if not empty
• front (front 1) MAXQSIZE
• To push, if not full
• Itemsback newitem
• back (back 1) MAXQSIZE
• Front returns itemsfront
• Alternate method without count items in range
  (front .. back
• Queue is empty if front back
• queue is full if (back1)MAXQSIZE front
• To push, if not full
• Back (back 1) MAXQSIZE
• itemsback newitem

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Bounded Queue d_bqueue.h

• const int MAXQSIZE 50
• template
• class bqueue
• public
• bqueue() // create empty queue of
  MAXQSIZE
• void push(const T item) // append item
  at back
• // Pre count exception
• void pop() // remove front item from
  queue
• // Pre queue is not empty
• T front() // return ref to front queue
  item
• const T front() const // ditto
• // Pre queue not empty
• int size() const // return the queue size
• bool empty() const // is the queue empty?
• bool full() const // is the queue full?
• private
• T queueArrayMAXQSIZE // queue items
  (circular array)

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Bounded Queue d_bqueue.h

• template
• bqueuebqueue() qfront(0), qback(0),
  count(0)
• template
• void bqueuepush(const T item)
• if (count MAXQSIZE) // array is
  full
• throw overflowError("bqueue push() queue
  full")
• queueArrayqback item // insert item
• qback (qback1) MAXQSIZE // move qback
  along
• count // increment
  size
• template
• void bqueuepop()
• if (count 0) // array is
  full
• throw underflowError("bqueue pop() empty
  queue")

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Bounded Queue d_bqueue.h

• template
• T bqueuefront()
• if (count 0) // queue is empty
• throw underflowError("bqueue front() empty
  q")
• return queueArrayqfront
• template
• const T bqueuefront() const
• if (count 0) // queue is empty
• throw underflowError("bqueue front() empty
  q")
• return queueArrayqfront

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Bounded Queue d_bqueue.h

• template
• int bqueuesize() const
• return count
• template
• bool bqueueempty() const
• return count 0
• template
• bool bqueuefull() const
• return count MAXQSIZE

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Simulation

• Simulations of interest to us are time driven
• Events are typically arrivals of entities seeking
  some service, benefit or access to a resource
• Arrival events over time may be generated
  randomly, uniformly or in accordance with a
  scripted sequence
• What we measure is waiting time, service time,
  resource utilization, etc
• Over time and multiple simulations using
  different constraints, the individual stats are
  summarized and compared to assess the best
  situation

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Simulation

• Example Customers at the drive-up bank teller
• Variables
• How many tellers are on duty
• How many drive-up lanes are open
• Time taken for a teller to serve a customer
• Use of Queues
• Each drive-up lane is represented by a queue with
  time of arrival stored for each customer waiting
• Tellers (vector of count-down timers)
• Tellerk is available if timer 0
• Tellerk is put to work by setting timer to time
  required for a given job

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Simulation main loop

• For each time interval
• Number of customer arrivals is determined
  (probabilistically)
• Lane placement of each arrival is determined
  (random or shortest-line or )
• Current time is pushed onto each queue getting a
  new arrival (this is the customers arrival time)
• For each available teller and waiting customer
• Customer in queue waiting longest is popped and
  assigned to teller
• Tellers counter is set to timer required
• Waiting time and total time for service are
  computed
• Current time is updated and all teller times are
  decremented by the interval

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Traffic Simulation

• Queues
• One for each lane of traffic entering
  intersection
• Arrivals determined by random chance, but based
  on know frequencies for time of day and real
  intersection
• Time of arrival kept in queue for each vehicle
• Rules of the road
• Assume no accidents
• Assume all drivers are law abiding
• Order of progression through intersection based
  on traffic rules (e.g., left turn yields to
  oncomming traffic unless left turn arrow, etc)

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Traffic Simulation

• Traffic lights
• No lights
• Lights, but no special turn arrows
• Lights with turn arrows
• Different light timing sequences
• Statistics
• Longest waiting time
• Average waiting time (each lane and overall)
• Average number of cars waiting at red light
• Number of cars through intersection
• ..

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Simulation

• Advanced options
• Light changes keyed to presence of cars in lane
• Simulation of grids of connected intersections
• Coordinated timing sequences at different
  intersections
• Simulations run for different times of day and
  different days of week (traffic arrival
  frequencies differ)
• Simulation of highway segment through multiple
  lights

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Review Topics to Date

• ADT, API, C classes
• Software design cycle
• Operator overloading
• Template functions and classes
• Sorting (Selection, Insertion, Shell, Merge,
  Quick, Radix, )
• Recursion (hanoi, fib, fact, knights, 8queens,)
• Containers (Vector, List, Dequeue)
• Containers (Sequence, adaptor, associative)
• Stacks Queues
• Dynamic Memory (new delete)
• Copy constructors, destructors, shallow vs. deep
• Singly-linked lists (will cover Tuesday)

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Test - Mechanics

• Closed book closed note in class
• EXCEPT
• You may use a standard C reference syntax sheet
  I will give you (and which will be posted on the
  web site)
• You may bring to the test and use while taking it
  any single 8.5 x 11 sheet of paper with
  anything you want written on it AS LONG AS it is
  hand written (NO TYPED AND REDUCED NOTES ALLOWED)
• Test will be short answer, code writing, code
  interpreting and analysis, maybe some T/F or
  multiple choice