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99 lines
2.8 KiB
99 lines
2.8 KiB
"""
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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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"""Queue class based on circular array"""
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def __init__(self, size: int):
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"""Constructor"""
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self._nums: list[int] = [0] * size # Array for storing queue elements
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self._front: int = 0 # Front pointer, pointing to the front element
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self._size: int = 0 # Queue length
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def capacity(self) -> int:
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"""Get the capacity of the queue"""
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return len(self._nums)
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def size(self) -> int:
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"""Get the length of the queue"""
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return self._size
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def is_empty(self) -> bool:
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"""Determine if the queue is empty"""
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return self._size == 0
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def push(self, num: int):
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"""Enqueue"""
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if self._size == self.capacity():
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raise IndexError("Queue is full")
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# Calculate rear pointer, pointing to rear index + 1
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# Use modulo operation to wrap the rear pointer from the end of the array back to the start
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rear: int = (self._front + self._size) % self.capacity()
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# Add num to the rear
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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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"""Dequeue"""
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num: int = self.peek()
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# Move front pointer one position backward, returning to the head of the array if it exceeds the tail
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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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"""Access front element"""
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if self.is_empty():
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raise IndexError("Queue is empty")
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return self._nums[self._front]
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def to_list(self) -> list[int]:
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"""Return array for printing"""
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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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# Initialize queue
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queue = ArrayQueue(10)
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# Element enqueue
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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("Queue queue =", queue.to_list())
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# Access front element
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peek: int = queue.peek()
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print("Front element peek =", peek)
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# Element dequeue
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pop: int = queue.pop()
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print("Dequeued element pop =", pop)
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print("Queue after dequeue =", queue.to_list())
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# Get the length of the queue
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size: int = queue.size()
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print("Queue length size =", size)
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# Determine if the queue is empty
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is_empty: bool = queue.is_empty()
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print("Is the queue empty =", is_empty)
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# Test circular array
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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("In the ", i, "th round of enqueue + dequeue, queue = ", queue.to_list())
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