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108 lines
3 KiB
Python
108 lines
3 KiB
Python
'''
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File: array_queue.py
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Created Time: 2022-12-01
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Author: Peng Chen (pengchzn@gmail.com)
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'''
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import os.path as osp
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import sys
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sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
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from include import *
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""" 基于环形数组实现的队列 """
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class ArrayQueue:
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def __init__(self, size):
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self.__nums = [0] * size # 用于存储队列元素的数组
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self.__front = 0 # 头指针，指向队首
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self.__rear = 0 # 尾指针，指向队尾 + 1
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""" 获取队列的容量 """
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def capacity(self):
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return len(self.__nums)
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""" 获取队列的长度 """
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def size(self):
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# 由于将数组看作为环形，可能 rear < front ，因此需要取余数
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return (self.capacity() + self.__rear - self.__front) % self.capacity()
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""" 判断队列是否为空 """
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def is_empty(self):
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return (self.__rear - self.__front) == 0
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""" 入队 """
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def push(self, val):
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if self.size() == self.capacity():
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print("队列已满")
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return False
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# 尾结点后添加 num
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self.__nums[self.__rear] = val
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# 尾指针向后移动一位，越过尾部后返回到数组头部
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self.__rear = (self.__rear + 1) % self.capacity()
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""" 出队 """
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def poll(self):
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# 删除头结点
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num = self.peek()
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# 队头指针向后移动一位，若越过尾部则返回到数组头部
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self.__front = (self.__front + 1) % self.capacity()
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return num
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""" 访问队首元素 """
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def peek(self):
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# 删除头结点
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if self.is_empty():
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print("队列为空")
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return False
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return self.__nums[self.__front]
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""" 访问指定位置元素 """
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def get(self, index):
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if index >= self.size():
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print("索引越界")
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return False
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return self.__nums[(self.__front + index) % self.capacity()]
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""" 返回列表用于打印 """
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def to_list(self):
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res = [0] * self.size()
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j = self.__front
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for i in range(self.size()):
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res[i] = self.__nums[(j % self.capacity())]
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j += 1
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return res
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""" Driver Code """
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if __name__ == "__main__":
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""" 初始化队列 """
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queue = ArrayQueue(10)
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""" 元素入队 """
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queue.push(1)
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queue.push(3)
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queue.push(2)
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queue.push(5)
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queue.push(4)
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print("队列 queue =", queue.to_list())
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""" 访问队首元素 """
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peek = queue.peek()
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print("队首元素 peek =", peek)
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""" 访问索引 index 处元素 """
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num = queue.get(3)
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print("队列索引 3 处的元素为 num =", num)
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""" 元素出队 """
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poll = queue.poll()
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print("出队元素 poll =", poll)
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print("出队后 queue =", queue.to_list())
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""" 获取队列的长度 """
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size = queue.size()
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print("队列长度 size =", size)
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""" 判断队列是否为空 """
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is_empty = queue.is_empty()
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print("队列是否为空 =", is_empty)
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