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# [9/25] 622. Design Circular Queue

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Medium

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.

Implementation the `MyCircularQueue` class:

• `MyCircularQueue(k)` Initializes the object with the size of the queue to be `k`.
• `int Front()` Gets the front item from the queue. If the queue is empty, return `-1`.
• `int Rear()` Gets the last item from the queue. If the queue is empty, return `-1`.
• `boolean enQueue(int value)` Inserts an element into the circular queue. Return `true` if the operation is successful.
• `boolean deQueue()` Deletes an element from the circular queue. Return `true` if the operation is successful.
• `boolean isEmpty()` Checks whether the circular queue is empty or not.
• `boolean isFull()` Checks whether the circular queue is full or not.

You must solve the problem without using the built-in queue data structure in your programming language.

Example 1:

```Input
["MyCircularQueue", "enQueue", "enQueue", "enQueue", "enQueue", "Rear", "isFull", "deQueue", "enQueue", "Rear"]
[[3], [1], [2], [3], [4], [], [], [], [4], []]
Output
[null, true, true, true, false, 3, true, true, true, 4]

Explanation
MyCircularQueue myCircularQueue = new MyCircularQueue(3);
myCircularQueue.enQueue(1); // return True
myCircularQueue.enQueue(2); // return True
myCircularQueue.enQueue(3); // return True
myCircularQueue.enQueue(4); // return False
myCircularQueue.Rear();     // return 3
myCircularQueue.isFull();   // return True
myCircularQueue.deQueue();  // return True
myCircularQueue.enQueue(4); // return True
myCircularQueue.Rear();     // return 4
```

Constraints:

• `1 <= k <= 1000`
• `0 <= value <= 1000`
• At most `3000` calls will be made to `enQueue``deQueue``Front``Rear``isEmpty`, and `isFull`.
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``````class MyCircularQueue:

def __init__(self, k: int):
self.max_size = k
self.data = [0]*k
self.front = 0
self.back = -1

def enQueue(self, value: int) -> bool:
if self.isFull(): return False
self.back = (self.back+1)%self.max_size
self.data[self.back] = value
return True

def deQueue(self) -> bool:
if self.isEmpty(): return False

if self.front == self.back:
self.front = 0
self.back = -1
else:
self.front = (self.front+1)%self.max_size

return True

def Front(self) -> int:
if self.isEmpty(): return -1
return self.data[self.front]

def Rear(self) -> int:
if self.isEmpty(): return -1
return self.data[self.back]

def isEmpty(self) -> bool:
return self.back == -1

def isFull(self) -> bool:
return self.back != -1 and (self.back+1)%self.max_size == self.front

# 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()``````
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