Python 使用循环数组实现队列 (基于class, 包含迭代器)

标签：算法与数据结构

#!/usr/bin/python 
# -*- coding: utf-8 -*-

'''
Created on 2015-2-2
@author: beyondzhou
@name: test_arryqueue.py
'''

def test_arryqueue():
    
    # import pyListQueue
    from myqueue import arrayQueue
    
    print '#Init a queue named smith using enqueue'
    smith = arrayQueue(4)
    smith.enqueue('CSCI-112')
    smith.enqueue('MATH-121')
    smith.enqueue('HIST-340')
    smith.enqueue('ECON-101')
    
    print '\n#output smith queue'
    for element in smith:
        print element
           
    print '\n#dequeue one item'
    smith.dequeue()
  
    print '\n#output smith after dequeue'
    for element in smith:
        print element 
        
    smith.enqueue('ECON-102')  
    print '\n#output smith after enqueue again'
    for element in smith:
        print element 
        
    print '\n#get the length of queue'
    print 'the lenght of queue is ', len(smith)
    
    print '\n#check wheter the queue is empty'
    if smith.isEmpty():
        print 'queue is empty!'
    else:
        print 'queue is not empty!'
        
    print '\n#dequeue all items'
    while not smith.isEmpty():
        smith.dequeue()
    
    print '\n#check wheter the queue is empty after dequeue all items'
    if smith.isEmpty():
        print 'queue is empty!'
    else:
        print 'queue is not empty!'
        
    print '\n#init again'
    smith.enqueue('CSCI-112')
    smith.enqueue('MATH-121')
    smith.enqueue('HIST-340')
    smith.enqueue('ECON-101')
    
    print '\n#output smith queue'
    for element in smith:
        print element
    
if __name__ == "__main__":
    test_arryqueue()

# Implementation of the Queue ADT using a circular array
class _ArrayQueueIterator:
    def __init__(self, theArray, front, count):
        self._arrayRef = theArray
        self._curNdx = front
        self._count = count
        self._index = 0

    def __iter__(self):
        return self

    def next(self):
        if self._index < self._count:
            entry = self._arrayRef[self._curNdx]
            self._curNdx = (self._curNdx+1) % len(self._arrayRef)
            self._index = self._index + 1
            return entry
        else:
            raise StopIteration
        
from myarray import Array

class arrayQueue:
    # Creates an empty queue
    def __init__(self, maxSize):
        self._count = 0
        self._front = 0
        self._back = maxSize - 1
        self._qArray = Array(maxSize)

    # Returns True if the queue is empty
    def isEmpty(self):
        return self._count == 0

    # Returns True if the queue is full
    def isFull(self):
        return self._count == len(self._qArray)

    # Returns the number of items in the queue
    def __len__(self):
        return self._count

    # Adds the given item to the queue
    def enqueue(self, item):
        assert not self.isFull(), "Cannot enqueue to a full queue."
        maxSize = len(self._qArray)
        self._back = (self._back + 1) % maxSize
        self._qArray[self._back] = item
        self._count += 1

    # Removes and returns the first item in the queue
    def dequeue(self):
        assert not self.isEmpty(), "Cannot dequeue from an empty queue."
        item = self._qArray[self._front]
        maxSize = len(self._qArray)
        self._front = (self._front + 1) % maxSize
        self._count -= 1
        return item
    
    # Returns the array queue's iterator for traversing the elements
    def __iter__(self):
        return _ArrayQueueIterator(self._qArray, self._front, self._count)

#Init a queue named smith using enqueue

#output smith queue
CSCI-112
MATH-121
HIST-340
ECON-101

#dequeue one item

#output smith after dequeue
MATH-121
HIST-340
ECON-101

#output smith after enqueue again
MATH-121
HIST-340
ECON-101
ECON-102

#get the length of queue
the lenght of queue is  4

#check wheter the queue is empty
queue is not empty!

#dequeue all items

#check wheter the queue is empty after dequeue all items
queue is empty!

#init again

#output smith queue
CSCI-112
MATH-121
HIST-340
ECON-101

Python 使用循环数组实现队列 (基于class, 包含迭代器)

标签：算法与数据结构

原文地址：http://blog.csdn.net/guaguastd/article/details/43411841