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* Revised the book * Update the book with the second revised edition * Revise base on the manuscript of the first edition
99 lines
2.6 KiB
Python
99 lines
2.6 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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class ArrayQueue:
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"""基于环形数组实现的队列"""
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def __init__(self, size: int):
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"""构造方法"""
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self._nums: list[int] = [0] * size # 用于存储队列元素的数组
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self._front: int = 0 # 队首指针，指向队首元素
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self._size: int = 0 # 队列长度
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def capacity(self) -> int:
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"""获取队列的容量"""
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return len(self._nums)
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def size(self) -> int:
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"""获取队列的长度"""
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return self._size
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def is_empty(self) -> bool:
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"""判断队列是否为空"""
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return self._size == 0
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def push(self, num: int):
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"""入队"""
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if self._size == self.capacity():
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raise IndexError("队列已满")
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# 计算队尾指针，指向队尾索引 + 1
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# 通过取余操作实现 rear 越过数组尾部后回到头部
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rear: int = (self._front + self._size) % self.capacity()
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# 将 num 添加至队尾
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self._nums[rear] = num
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self._size += 1
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def pop(self) -> int:
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"""出队"""
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num: int = self.peek()
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# 队首指针向后移动一位，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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self._size -= 1
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return num
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def peek(self) -> int:
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"""访问队首元素"""
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if self.is_empty():
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raise IndexError("队列为空")
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return self._nums[self._front]
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def to_list(self) -> list[int]:
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"""返回列表用于打印"""
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res = [0] * self.size()
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j: int = 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: int = queue.peek()
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print("队首元素 peek =", peek)
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# 元素出队
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pop: int = queue.pop()
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print("出队元素 pop =", pop)
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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: int = 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: bool = queue.is_empty()
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print("队列是否为空 =", is_empty)
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# 测试环形数组
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for i in range(10):
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queue.push(i)
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queue.pop()
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print("第", i, "轮入队 + 出队后 queue = ", queue.to_list())
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