You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
130 lines
3.8 KiB
130 lines
3.8 KiB
"""
|
|
File: array_deque.py
|
|
Created Time: 2023-03-01
|
|
Author: Krahets (krahets@163.com)
|
|
"""
|
|
|
|
|
|
class ArrayDeque:
|
|
"""基于环形数组实现的双向队列"""
|
|
|
|
def __init__(self, capacity: int):
|
|
"""构造方法"""
|
|
self._nums: list[int] = [0] * capacity
|
|
self._front: int = 0
|
|
self._size: int = 0
|
|
|
|
def capacity(self) -> int:
|
|
"""获取双向队列的容量"""
|
|
return len(self._nums)
|
|
|
|
def size(self) -> int:
|
|
"""获取双向队列的长度"""
|
|
return self._size
|
|
|
|
def is_empty(self) -> bool:
|
|
"""判断双向队列是否为空"""
|
|
return self._size == 0
|
|
|
|
def index(self, i: int) -> int:
|
|
"""计算环形数组索引"""
|
|
# 通过取余操作实现数组首尾相连
|
|
# 当 i 越过数组尾部后，回到头部
|
|
# 当 i 越过数组头部后，回到尾部
|
|
return (i + self.capacity()) % self.capacity()
|
|
|
|
def push_first(self, num: int):
|
|
"""队首入队"""
|
|
if self._size == self.capacity():
|
|
print("双向队列已满")
|
|
return
|
|
# 队首指针向左移动一位
|
|
# 通过取余操作实现 front 越过数组头部后回到尾部
|
|
self._front = self.index(self._front - 1)
|
|
# 将 num 添加至队首
|
|
self._nums[self._front] = num
|
|
self._size += 1
|
|
|
|
def push_last(self, num: int):
|
|
"""队尾入队"""
|
|
if self._size == self.capacity():
|
|
print("双向队列已满")
|
|
return
|
|
# 计算队尾指针，指向队尾索引 + 1
|
|
rear = self.index(self._front + self._size)
|
|
# 将 num 添加至队尾
|
|
self._nums[rear] = num
|
|
self._size += 1
|
|
|
|
def pop_first(self) -> int:
|
|
"""队首出队"""
|
|
num = self.peek_first()
|
|
# 队首指针向后移动一位
|
|
self._front = self.index(self._front + 1)
|
|
self._size -= 1
|
|
return num
|
|
|
|
def pop_last(self) -> int:
|
|
"""队尾出队"""
|
|
num = self.peek_last()
|
|
self._size -= 1
|
|
return num
|
|
|
|
def peek_first(self) -> int:
|
|
"""访问队首元素"""
|
|
if self.is_empty():
|
|
raise IndexError("双向队列为空")
|
|
return self._nums[self._front]
|
|
|
|
def peek_last(self) -> int:
|
|
"""访问队尾元素"""
|
|
if self.is_empty():
|
|
raise IndexError("双向队列为空")
|
|
# 计算尾元素索引
|
|
last = self.index(self._front + self._size - 1)
|
|
return self._nums[last]
|
|
|
|
def to_array(self) -> list[int]:
|
|
"""返回数组用于打印"""
|
|
# 仅转换有效长度范围内的列表元素
|
|
res = []
|
|
for i in range(self._size):
|
|
res.append(self._nums[self.index(self._front + i)])
|
|
return res
|
|
|
|
|
|
"""Driver Code"""
|
|
if __name__ == "__main__":
|
|
# 初始化双向队列
|
|
deque = ArrayDeque(10)
|
|
deque.push_last(3)
|
|
deque.push_last(2)
|
|
deque.push_last(5)
|
|
print("双向队列 deque =", deque.to_array())
|
|
|
|
# 访问元素
|
|
peek_first: int = deque.peek_first()
|
|
print("队首元素 peek_first =", peek_first)
|
|
peek_last: int = deque.peek_last()
|
|
print("队尾元素 peek_last =", peek_last)
|
|
|
|
# 元素入队
|
|
deque.push_last(4)
|
|
print("元素 4 队尾入队后 deque =", deque.to_array())
|
|
deque.push_first(1)
|
|
print("元素 1 队首入队后 deque =", deque.to_array())
|
|
|
|
# 元素出队
|
|
pop_last: int = deque.pop_last()
|
|
print("队尾出队元素 =", pop_last, "，队尾出队后 deque =", deque.to_array())
|
|
pop_first: int = deque.pop_first()
|
|
print("队首出队元素 =", pop_first, "，队首出队后 deque =", deque.to_array())
|
|
|
|
# 获取双向队列的长度
|
|
size: int = deque.size()
|
|
print("双向队列长度 size =", size)
|
|
|
|
# 判断双向队列是否为空
|
|
is_empty: bool = deque.is_empty()
|
|
print("双向队列是否为空 =", is_empty)
|