Add array_deque.py and linkedlist_deque.py (#399)

codes/python/chapter_stack_and_queue/array_deque.py

@@ -0,0 +1,131 @@
+"""
+File: array_deque.py
+Created Time: 2023-03-01
+Author: Krahets (krahets@163.com)
+"""
+
+import os.path as osp
+import sys
+
+sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
+from include import *
+
+""" 基于环形数组实现的双向队列 """
+class ArrayDeque:
+    """  构造方法 """
+    def __init__(self, capacity):
+        self.nums = [0] * capacity
+        self.front = 0
+        self.que_size = 0
+
+    """  获取双向队列的容量  """
+    def capacity(self):
+        return len(self.nums)
+
+    """ 获取双向队列的长度  """
+    def size(self):
+        return self.que_size
+
+    """ 判断双向队列是否为空 """
+    def is_empty(self):
+        return self.que_size == 0
+
+    """ 计算环形数组索引 """
+    def index(self, i):
+        # 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()
+
+    """ 队首入队 """
+    def push_first(self, num):
+        if self.que_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.que_size += 1
+
+    """ 队尾入队 """
+    def push_last(self, num):
+        if self.que_size == self.capacity():
+            print("双向队列已满")
+            return
+        # 计算尾指针，指向队尾索引 + 1
+        rear = self.index(self.front + self.que_size)
+        # 将 num 添加至队尾
+        self.nums[rear] = num
+        self.que_size += 1
+
+    """ 队首出队 """
+    def poll_first(self):
+        num = self.peek_first()
+        # 队首指针向后移动一位
+        self.front = self.index(self.front+1)
+        self.que_size -= 1
+        return num
+
+    """ 队尾出队 """
+    def poll_last(self):
+        num = self.peek_last()
+        self.que_size -= 1
+        return num
+
+    """ 访问队首元素 """
+    def peek_first(self):
+        assert not self.is_empty(), "双向队列为空"
+        return self.nums[self.front]
+
+    """ 访问队尾元素 """
+    def peek_last(self):
+        assert not self.is_empty(), "双向队列为空"
+        # 计算尾元素索引
+        last = self.index(self.front + self.que_size - 1)
+        return self.nums[last]
+
+    """ 返回数组用于打印 """
+    def to_array(self):
+        # 仅转换有效长度范围内的列表元素
+        res = []
+        for i in range(self.que_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 = deque.peek_first()
+    print("队首元素 peek_first =", peek_first)
+    peek_last = 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 """
+    poll_last = deque.poll_last()
+    print("队尾出队元素 =", poll_last, "，队尾出队后 deque =", deque.to_array())
+    poll_first = deque.poll_first()
+    print("队首出队元素 =", poll_first, "，队首出队后 deque =", deque.to_array())
+
+    """ 获取双向队列的长度 """
+    size = deque.size()
+    print("双向队列长度 size =", size)
+
+    """ 判断双向队列是否为空 """
+    is_empty = deque.is_empty()
+    print("双向队列是否为空 =", is_empty)