[9/25] 622. Design Circular Queue
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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 bek.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. Returntrueif the operation is successful.boolean deQueue()Deletes an element from the circular queue. Returntrueif 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 <= 10000 <= value <= 1000- At most
3000calls will be made toenQueue,deQueue,Front,Rear,isEmpty, andisFull.
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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()
