Created
August 13, 2012 02:39
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PriorityQueue
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| require 'set' | |
| class PriorityQueue | |
| def initialize | |
| @pq = SortedSet.new | |
| end | |
| def insert key, value | |
| entry = find(key) || Entry.new(key) | |
| entry.add(value) | |
| @pq << entry | |
| end | |
| def find(search_key) | |
| found = nil | |
| @pq.each do |entry| | |
| if entry.key == search_key | |
| found = entry | |
| end | |
| end | |
| found | |
| end | |
| def remove | |
| entry = @pq.first | |
| @pq.delete(entry) | |
| entry_value = entry.remove() | |
| if entry.size > 0 | |
| @pq << entry | |
| end | |
| entry_value | |
| end | |
| end | |
| class Entry | |
| include Comparable | |
| attr_reader :key, :list | |
| def initialize(key) | |
| @key = key | |
| @list = [] | |
| end | |
| def add(value) | |
| list << value | |
| end | |
| def remove() | |
| list.shift | |
| end | |
| def size() | |
| list.size | |
| end | |
| def <=>(other) | |
| other.key <=> self.key | |
| end | |
| end |
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| require 'priority_queue.rb' | |
| describe PriorityQueue do | |
| before { @pq = PriorityQueue.new } | |
| it 'can pull the highest priority item' do | |
| @pq.insert 1, "A" | |
| @pq.insert 25, "B" | |
| @pq.insert 1, "C" | |
| @pq.insert 25, "D" | |
| @pq.remove().should eq "B" | |
| @pq.remove().should eq "D" | |
| @pq.remove().should eq "A" | |
| @pq.remove().should eq "C" | |
| end | |
| describe Entry do | |
| it 'should compare' do | |
| e = Entry.new(2) | |
| e2 = Entry.new(1) | |
| value = e.<=> e2 | |
| value.should eq(-1) | |
| end | |
| it 'should act like a queue' do | |
| e = Entry.new(2) | |
| e.add "A" | |
| e.add "B" | |
| e.add "C" | |
| e.remove.should eq "A" | |
| e.remove.should eq "B" | |
| e.remove.should eq "C" | |
| end | |
| end | |
| end |
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