Python - 数据结构之出队

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  简述

  双端队列或双端队列支持从任一端添加和删除元素。更常用的堆栈和队列是双端队列的退化形式，其中输入和输出被限制在一个端。
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  例子

  
  import collections
  
  DoubleEnded = collections.deque(["Mon","Tue","Wed"])
  DoubleEnded.append("Thu")
  
  print ("Appended at right - ")
  print (DoubleEnded)
  
  DoubleEnded.appendleft("Sun")
  print ("Appended at right at left is - ")
  print (DoubleEnded)
  
  DoubleEnded.pop()
  print ("Deleting from right - ")
  print (DoubleEnded)
  
  DoubleEnded.popleft()
  print ("Deleting from left - ")
  print (DoubleEnded)
  

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  输出

  执行上述代码时，会产生以下结果 -

  
  Appended at right - 
  deque(['Mon', 'Tue', 'Wed', 'Thu'])
  Appended at right at left is - 
  deque(['Sun', 'Mon', 'Tue', 'Wed', 'Thu'])
  Deleting from right - 
  deque(['Sun', 'Mon', 'Tue', 'Wed'])
  Deleting from left - 
  deque(['Mon', 'Tue', 'Wed'])