641. Design Circular Deque.py

'''
这题与622. Design Circular Queue不同，由于两端都要操作，最好让front和rear正好指向两端，
然后空的时候加上if/else checks

这题可以用array也可以用doubly linked list
doubly linked list可以用head node来处理edge cases，不需要tail，连成环形就行
'''

class MyCircularDeque:

    def __init__(self, k: int):
        """
        Initialize your data structure here. Set the size of the deque to be k.
        """
        self.array = [0] * k
        self.size = 0
        self.capacity = k
        self.front = 0
        self.rear = 0

    def insertFront(self, value: int) -> bool:
        """
        Adds an item at the front of Deque. Return true if the operation is successful.
        """
        if self.isFull():
            return False
        if not self.isEmpty():
            self.front = (self.front - 1 + self.capacity) % self.capacity
        self.array[self.front] = value
        self.size += 1
        return True

    def insertLast(self, value: int) -> bool:
        """
        Adds an item at the rear of Deque. Return true if the operation is successful.
        """
        if self.isFull():
            return False
        if not self.isEmpty():
            self.rear = (self.rear + 1) % self.capacity
        self.array[self.rear] = value
        self.size += 1
        return True

    def deleteFront(self) -> bool:
        """
        Deletes an item from the front of Deque. Return true if the operation is successful.
        """
        if self.isEmpty():
            return False
        if self.size != 1:
            self.front = (self.front + 1) % self.capacity
        self.size -= 1
        return True

    def deleteLast(self) -> bool:
        """
        Deletes an item from the rear of Deque. Return true if the operation is successful.
        """
        if self.isEmpty():
            return False
        if self.size != 1:
            self.rear = (self.rear - 1 + self.capacity) % self.capacity
        self.size -= 1
        return True

    def getFront(self) -> int:
        """
        Get the front item from the deque.
        """
        if self.isEmpty():
            return -1
        else:
            return self.array[self.front]

    def getRear(self) -> int:
        """
        Get the last item from the deque.
        """
        if self.isEmpty():
            return -1
        else:
            return self.array[self.rear]

    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