implementation of ArrayQueue and CircularQueue in Python

python/09_queue/array_queue.py

@@ -0,0 +1,33 @@
+"""
+    Queue based upon array
+    用数组实现的队列
+
+    Author: Wenru
+"""
+
+from typing import Optional
+
+class ArrayQueue:
+
+    def __init__(self, capacity: int):
+        self._items = []
+        self._capacity = capacity
+        self._head = 0
+        self._tail = 0
+
+    def enqueue(self, item: str) -> bool:
+        if self._tail == self._capacity: return False
+
+        self._items.append(item)
+        self._tail += 1
+        return True
+
+    def dequeue(self) -> Optional[str]:
+        if self._head != self._tail:
+            item = self._items[self._head]
+            self._head += 1
+            return item
+
+    def __repr__(self) -> str:
+        return " ".join(item for item in self._items[self._head : self._tail])
+

python/09_queue/circular_queue.py

@@ -0,0 +1,43 @@
+"""
+    Author: Wenru
+"""
+
+from typing import Optional
+from itertools import chain
+
+class CircularQueue:
+
+    def __init__(self, capacity):
+        self._items = []
+        self._capacity = capacity + 1
+        self._head = 0
+        self._tail = 0
+
+    def enqueue(self, item: str) -> bool:
+        if (self._tail + 1) % self._capacity == self._head:
+            return False
+
+        self._items.append(item)
+        self._tail = (self._tail + 1) % self._capacity
+        return True
+
+    def dequeue(self) -> Optional[str]:
+        if self._head != self._tail:
+            item = self._items[self._head]
+            self._head = (self._head + 1) % self._capacity
+            return item
+
+    def __repr__(self) -> str:
+        if self._tail >= self._head:
+            return " ".join(item for item in self._items[self._head : self._tail])
+        else:
+            return " ".join(item for item in chain(self._items[self._head:], self._items[:self._tail]))
+
+if __name__ == "__main__":
+    q = CircularQueue(5)
+    for i in range(5):
+        q.enqueue(str(i))
+    q.dequeue()
+    q.dequeue()
+    q.enqueue(str(5))
+    print(q)