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.
Example:
MyCircularQueue circularQueue = new MyCircularQueue(3); // set the size to be 3 circularQueue.enQueue(1); // return true circularQueue.enQueue(2); // return true circularQueue.enQueue(3); // return true circularQueue.enQueue(4); // return false, the queue is full circularQueue.Rear(); // return 3 circularQueue.isFull(); // return true circularQueue.deQueue(); // return true circularQueue.enQueue(4); // return true circularQueue.Rear(); // return 4
Note:
- All values will be in the range of [0, 1000].
- The number of operations will be in the range of [1, 1000].
- Please do not use the built-in Queue library.
Similar Questions:
// OJ: https://leetcode.com/problems/design-circular-queue/
// Author: github.com/lzl124631x
// Time: O(1) for all
// Space: O(K)
class MyCircularQueue {
private:
vector<int> v;
int start = 0, len = 0;
public:
MyCircularQueue(int k): v(k) {}
bool enQueue(int value) {
if (isFull()) return false;
v[(start + len++) % v.size()] = value;
return true;
}
bool deQueue() {
if (isEmpty()) return false;
start = (start + 1) % v.size();
--len;
return true;
}
int Front() {
if (isEmpty()) return -1;
return v[start];
}
int Rear() {
if (isEmpty()) return -1;
return v[(start + len - 1) % v.size()];
}
bool isEmpty() {
return !len;
}
bool isFull() {
return len == v.size();
}
};