circular_dequeue.py

class MyCircularDeque:

    def __init__(self, k: int):
        """
        Initialize your data structure here. Set the size of the deque to be k.
        """
        self._capacity = k
        self._size = 0
        self._queue = [None] * self._capacity
        self._head = None
        self._tail = None
        
    def _check_bounderies(self, index):
        if index < 0:
            return self._capacity - 1
        elif index >= self._capacity:
            return 0
        return index
        
    def _set_tail(self, new_tail):
        self._tail = self._check_bounderies(new_tail)
        
    def _set_head(self, new_head):
        self._head = self._check_bounderies(new_head)
    
    def insertFront(self, value: int) -> bool:
        """
        Adds an item at the front of Deque. Return true if the operation is successful.
        """
        if not self.isFull():
            if self._head is None or self._tail is None:
                self._head = 0
                self._tail = 0
            else:
                self._set_head(self._head - 1)
            self._queue[self._head] = value
            self._size += 1
            return True
        else:
            return False
        

    def insertLast(self, value: int) -> bool:
        """
        Adds an item at the rear of Deque. Return true if the operation is successful.
        """
        if not self.isFull():
            if self._head is None or self._tail is None:
                self._head = 0
                self._tail = 0
            else:
                self._set_tail(self._tail + 1)
            self._queue[self._tail] = value
            self._size += 1
            return True
        else:
            return False
        

    def deleteFront(self) -> bool:
        """
        Deletes an item from the front of Deque. Return true if the operation is successful.
        """
        if not self.isEmpty():
            self._queue[self._head] = None
            self._set_head(self._head + 1)
            self._size -= 1
            return True
        else:
            return False

    def deleteLast(self) -> bool:
        """
        Deletes an item from the rear of Deque. Return true if the operation is successful.
        """
        if not self.isEmpty():
            self._queue[self._tail] = None
            self._set_tail(self._tail - 1)
            self._size -= 1
            return True
        else:
            return False
        

    def getFront(self) -> int:
        """
        Get the front item from the deque.
        """
        if not self.isEmpty():
            return self._queue[self._head]
        else:
            return -1

    def getRear(self) -> int:
        """
        Get the last item from the deque.
        """
        if not self.isEmpty():
            return self._queue[self._tail]
        else:
            return -1
        

    def isEmpty(self) -> bool:
        """
        Checks whether the circular deque is empty or not.
        """
        return self._size == 0
        

    def isFull(self) -> bool:
        """
        Checks whether the circular deque is full or not.
        """
        return self._size == self._capacity