Design Circular Deque

Intuition

Solution

#!/usr/bin/env python
# coding=utf-8
#
# Author: Lucas
# Date: 2019-09-01 23:35:44


class MyCircularDeque:
    def __init__(self, k: int):
        """
        Initialize your data structure here. Set the size of the deque to be k.
        """
        self.size = k
        self.data = [None] * (3 * k)
        self.start = k
        self.end = k

    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 self.start == 0:
            for i in range(self.start, self.end):
                self.data[i + self.size] = self.data[i]
                self.data[i] = None
            self.start += self.size
            self.end += self.size
        self.start -= 1
        self.data[self.start] = value
        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 self.end == len(self.data):
            for i in range(self.start, self.end):
                self.data[i - self.size] = self.data[i]
                self.data[i] = None
            self.start -= self.size
            self.end -= self.size
        self.data[self.end] = value
        self.end += 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
        self.data[self.start] = None
        self.start += 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
        self.end -= 1
        self.data[self.end] = None
        return True

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

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

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


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


# Your MyCircularDeque object will be instantiated and called as such:
# obj = MyCircularDeque(k)
# param_1 = obj.insertFront(value)
# param_2 = obj.insertLast(value)
# param_3 = obj.deleteFront()
# param_4 = obj.deleteLast()
# param_5 = obj.getFront()
# param_6 = obj.getRear()
# param_7 = obj.isEmpty()
# param_8 = obj.isFull()