mirror of
https://github.com/TheAlgorithms/Ruby
synced 2024-12-27 21:58:57 +01:00
106 lines
2.3 KiB
Ruby
106 lines
2.3 KiB
Ruby
# A queue is like a waiting list.
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# Imagine you are waiting in line to buy the latest Android product
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# or getting a parking ticket. These are queues!
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#
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#
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# 1. An array can behave like a Queue if you use the right methods.
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#
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# These methods are:
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# - unshift: when you unshift, you are adding one item to the queue
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# - pop
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#
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class ArrayQueue
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def initialize(queue = [])
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@queue = queue
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end
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attr_accessor :queue
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def add(item)
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queue.unshift(item)
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end
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def pop
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queue.pop
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end
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def peek
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queue[-1]
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end
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end
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queue = ArrayQueue.new
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queue.add(3)
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queue.add(4)
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queue.add(5)
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puts queue.inspect
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# => #<ArrayQueue:0x00007fc78200f5e0 @queue=[5, 4, 3]>
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queue.pop
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puts queue.inspect
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# => #<ArrayQueue:0x00007fc78200f5e0 @queue=[5, 4]>
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puts(queue.peek)
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# => 4
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#
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#
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# 2. Ruby Concurrent Queue
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# Ruby has a proper thread-safe, blocking, Queue class.
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# You can use this queue for coordinating work in a multi-threaded program.
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#
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# Reference: https://ruby-doc.org/core-2.5.0/Queue.html
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#
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queue = Queue.new
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queue << 1
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queue << 2
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queue << 3
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queue.pop
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# 1
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queue.pop
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# 2
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# If the queue is empty, calling pop will put your current
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# thread to sleep & wait until something is added to the queue.
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#
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#
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# 3. How to Use a Ruby SizedQueue
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# A sized queue is the same as a regular queue but with a size limit.
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#
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# Reference: https://ruby-doc.org/core-2.5.0/SizedQueue.html
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#
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queue = SizedQueue.new(5)
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# When the queue is full, the push (same as <<) operation
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# will suspend the current thread until an item is taken off the queue.
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queue.push(:oranges)
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queue.push(:apples)
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queue.push(:blue)
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queue.push(:orange)
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queue.push(:green)
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# At this point, the SizedQueue is full
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queue.push(:throw_expection)
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# data_structures/queues/queue.rb:81:in `push': No live threads left. Deadlock? (fatal)
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# 1 threads, 1 sleeps current:0x00007ff54f407130 main thread:0x00007ff54f407130
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# * #<Thread:0x00007ff54f86ef38 sleep_forever>
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# rb_thread_t:0x00007ff54f407130 native:0x000000010dd24dc0 int:0
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# data_structures/queues/queue.rb:81:in `push'
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# data_structures/queues/queue.rb:81:in `<main>'
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# from data_structures/queues/queue.rb:81:in `<main>'
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# You can choose to raise an exception, passing true as an argument as follows:
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queue.push(:throw_expection, true)
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# data_structures/queues/queue.rb:83:in `push': queue full (ThreadError)
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# from data_structures/queues/queue.rb:83:in `<main>'
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