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  1. class queuearray:
  2.     DefaultCapacity=10
  3.     def __init__(self):
  4.         #create an empty list of nones 
  5.         self.data=[None]*self.DefaultCapacity
  6.         self.size=0
  7.         self.front=0
  8.     def __len__(self):
  9.         return self.size
  10.     def is_empty(self):
  11.         return self.size==0
  12.     def first(self):
  13.         if self.is_empty():
  14.             raise Exception('Queue Is Empty')
  15.         return self.data[self.front]
  16.     def dequeue(self):
  17.         if self.is_empty():
  18.             raise Exception('Queue Is Empty')
  19.         answer=self.data[self.front]
  20.         self.data[self.front]=None
  21.         self.front=(self.front+1)%len(self.data)
  22.         self.size-=1
  23.         return answer
  24.     def enqueue(self,e):
  25.         if self.size==self.DefaultCapacity:
  26.             self.resize(2*len(self.data))    
  27.         aval=(self.front+self.size)%len(self.data)    
  28.         self.data[aval]=e
  29.         self.size+=1
  30.     def resize(self,cap):
  31.         old=self.data
  32.         #build a new list of anew size have nones 
  33.         self.data=[None]*cap
  34.         walk=self.front
  35.         for k in range(self.size):
  36.             self.data[k]=old[walk]
  37.             walk=(1+walk)%len(old)
  38.         self.front=0
  39.  
  40. s=queuearray()
  41. #s.dequeue()
  42. s.enqueue(5)
  43. print(s.first())
  44. s.enqueue(30)
  45. s.enqueue(40)
  46. print(s.first())
  47.  
Success #stdin #stdout 0.01s 7236KB
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https://ideone.com/LRyQzr
language:
Python (cpython 2.7.16)
created:
4 days ago
visibility:
public

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