0622_design_circular_queue.py

# ------------------------------------------------------------------------------
# Question:
# ------------------------------------------------------------------------------
# tags:
'''
Design your implementation of the circular queue. The circular queue is a
linear data structure in which the operations are performed based on FIFO
(First In First Out) principle and the last
position is connected back to the first position to make a circle. It is also
called "Ring Buffer".

One of the benefits of the circular queue is that we can make use of the spaces
in front of the queue. In a normal queue, once the queue becomes full, we cannot
insert the next element even if there is a space in front of the queue. But
using the circular queue, we can use the space to store new values.

Your implementation should support following operations:

MyCircularQueue(k): Constructor, set the size of the queue to be k.
Front: Get the front item from the queue. If the queue is empty, return -1.
Rear: Get the last item from the queue. If the queue is empty, return -1.
enQueue(value): Insert an element into the circular queue. Return true if the operation is successful.
deQueue(): Delete an element from the circular queue. Return true if the operation is successful.
isEmpty(): Checks whether the circular queue is empty or not.
isFull(): Checks whether the circular queue is full or not.
 

'''

# ------------------------------------------------------------------------------
# Solutions
# ------------------------------------------------------------------------------

import unittest
from typing import *


class Node():
    def __init__(self, v):
        self.data = v
        self.next = None

class MyCircularQueue:
    '''

    H -> q1
         T
    '''

    def __init__(self, k: int):
        """
        Initialize your data structure here. Set the size of the queue to be k.
        """
        self.head = None
        self.tail = None
        self.size = 0
        self.maxSize = k

    def enQueue(self, value: int) -> bool:
        """
        Insert an element into the circular queue. Return true if the operation is successful.
        """
        if self.isFull(): return False

        node = Node(value)
        if self.head is None:
            self.head = node
            self.tail = node
        else:
            self.tail.next = node
            self.tail = node
        self.size += 1
        return True


    def deQueue(self) -> bool:
        """
        Delete an element from the circular queue. Return true if the operation is successful.
        """
        if not self.head:
            return False

        self.head = self.head.next
        self.size -= 1
        if self.head is None:
            self.tail = self.head
        return True

    def Front(self) -> int:
        """
        Get the front item from the queue.
        """
        if not self.head:
            return -1
        if self.head:
            return self.head.value

    def Rear(self) -> int:
        """
        Get the last item from the queue.
        """
        if not self.tail:
            return -1
        return self.tail.value

    def isEmpty(self) -> bool:
        """
        Checks whether the circular queue is empty or not.
        """
        if not self.head and not self.tail:
            return True
        return False

    def isFull(self) -> bool:
        """
        Checks whether the circular queue is full or not.
        """
        if self.maxSize == self.count:
            return True
        return False


# Your MyCircularQueue object will be instantiated and called as such:
# obj = MyCircularQueue(k)
# param_1 = obj.enQueue(value)
# param_2 = obj.deQueue()
# param_3 = obj.Front()
# param_4 = obj.Rear()
# param_5 = obj.isEmpty()
# param_6 = obj.isFull()


# ------------------------------------------------------------------------------
# Tests
# ------------------------------------------------------------------------------

class TestSolution(unittest.TestCase):
    def test_simple(self):
        s = Solution()
        self.assertEqual(True, True)


unittest.main(verbosity=2)