Data commit

Task/Priority-queue/Ruby/priority-queue.rb

@@ -0,0 +1,82 @@
+class PriorityQueueNaive
+  def initialize(data=nil)
+    @q = Hash.new {|h, k| h[k] = []}
+    data.each {|priority, item| @q[priority] << item}  if data
+    @priorities = @q.keys.sort
+  end
+
+  def push(priority, item)
+    @q[priority] << item
+    @priorities = @q.keys.sort
+  end
+
+  def pop
+    p = @priorities[0]
+    item = @q[p].shift
+    if @q[p].empty?
+      @q.delete(p)
+      @priorities.shift
+    end
+    item
+  end
+
+  def peek
+    unless empty?
+      @q[@priorities[0]][0]
+    end
+  end
+
+  def empty?
+    @priorities.empty?
+  end
+
+  def each
+    @q.each do |priority, items|
+      items.each {|item| yield priority, item}
+    end
+  end
+
+  def dup
+    @q.each_with_object(self.class.new) do |(priority, items), obj|
+      items.each {|item| obj.push(priority, item)}
+    end
+  end
+
+  def merge(other)
+    raise TypeError  unless self.class == other.class
+    pq = dup
+    other.each {|priority, item| pq.push(priority, item)}
+    pq                  # return a new object
+  end
+
+  def inspect
+    @q.inspect
+  end
+end
+
+test = [
+  [6, "drink tea"],
+  [3, "Clear drains"],
+  [4, "Feed cat"],
+  [5, "Make tea"],
+  [6, "eat biscuit"],
+  [1, "Solve RC tasks"],
+  [2, "Tax return"],
+]
+
+pq = PriorityQueueNaive.new
+test.each {|pr, str| pq.push(pr, str) }
+until pq.empty?
+  puts pq.pop
+end
+
+puts
+test2 = test.shift(3)
+p pq1 = PriorityQueueNaive.new(test)
+p pq2 = PriorityQueueNaive.new(test2)
+p pq3 = pq1.merge(pq2)
+puts "peek : #{pq3.peek}"
+until pq3.empty?
+  puts pq3.pop
+end
+puts "peek : #{pq3.peek}"