设计实现双端队列。
你的实现需要支持以下操作：
MyCircularDeque(k)：构造函数,双端队列的大小为k。
insertFront()：将一个元素添加到双端队列头部。 如果操作成功返回 true。
insertLast()：将一个元素添加到双端队列尾部。如果操作成功返回 true。
deleteFront()：从双端队列头部删除一个元素。 如果操作成功返回 true。
deleteLast()：从双端队列尾部删除一个元素。如果操作成功返回 true。
getFront()：从双端队列头部获得一个元素。如果双端队列为空，返回 -1。
getRear()：获得双端队列的最后一个元素。 如果双端队列为空，返回 -1。
isEmpty()：检查双端队列是否为空。
isFull()：检查双端队列是否满了。
示例：
MyCircularDeque circularDeque = new MycircularDeque(3); // 设置容量大小为3
circularDeque.insertLast(1); // 返回 true
circularDeque.insertLast(2); // 返回 true
circularDeque.insertFront(3); // 返回 true
circularDeque.insertFront(4); // 已经满了，返回 false
circularDeque.getRear(); // 返回 2
circularDeque.isFull(); // 返回 true
circularDeque.deleteLast(); // 返回 true
circularDeque.insertFront(4); // 返回 true
circularDeque.getFront(); // 返回 4
提示：
所有值的范围为 [1, 1000]
操作次数的范围为 [1, 1000]
请不要使用内置的双端队列库。
C#版：
public class MyCircularDeque {
public int[] _deque;
public int _length=0;
public int _front=0;
public int _rear=0;
public int _maxsize;
/** Initialize your data structure here. Set the size of the deque to be k. */
public MyCircularDeque(int k) {
_deque=new int[k];
_maxsize=k;
}
/** Adds an item at the front of Deque. Return true if the operation is successful. */
public bool InsertFront(int value) {
if(IsFull())
return false;
_front=(_front-1+_maxsize)%_maxsize;
_deque[_front]=value;
_length++;
return true;
}
/** Adds an item at the rear of Deque. Return true if the operation is successful. */
public bool InsertLast(int value) {
if(IsFull())
return false;
_deque[_rear]=value;
_rear=(_rear+1)%_maxsize;
_length++;
return true;
}
/** Deletes an item from the front of Deque. Return true if the operation is successful. */
public bool DeleteFront() {
if(IsEmpty())
return false;
_front=(_front+1)%_maxsize;
_length--;
return true;
}
/** Deletes an item from the rear of Deque. Return true if the operation is successful. */
public bool DeleteLast() {
if(IsEmpty())
return false;
_rear=(_rear-1+_maxsize)%_maxsize;
_length--;
return true;
}
/** Get the front item from the deque. */
public int GetFront() {
if(IsEmpty())
return -1;
return _deque[_front];
}
/** Get the last item from the deque. */
public int GetRear() {
if(IsEmpty())
return -1;
return _deque[(_rear-1+_maxsize)%_maxsize];
}
/** Checks whether the circular deque is empty or not. */
public bool IsEmpty() {
return _length==0;
}
/** Checks whether the circular deque is full or not. */
public bool IsFull() {
return _length==_maxsize;
}
}
/**
* Your MyCircularDeque object will be instantiated and called as such:
* MyCircularDeque obj = new MyCircularDeque(k);
* bool param_1 = obj.InsertFront(value);
* bool param_2 = obj.InsertLast(value);
* bool param_3 = obj.DeleteFront();
* bool param_4 = obj.DeleteLast();
* int param_5 = obj.GetFront();
* int param_6 = obj.GetRear();
* bool param_7 = obj.IsEmpty();
* bool param_8 = obj.IsFull();
*/
C++版：
class MyCircularDeque {
public:
/** Initialize your data structure here. Set the size of the deque to be k. */
vector<int> deque;
int pfront=0;
int prear=0;
int length=0;
int maxsize;
MyCircularDeque(int k) {
deque.assign(k, 0);
maxsize=k;
}
/** Adds an item at the front of Deque. Return true if the operation is successful. */
bool insertFront(int value) {
if(length==maxsize)
return false;
pfront=(pfront-1+maxsize)%maxsize;
deque[pfront]=value;
length++;
return true;
}
/** Adds an item at the rear of Deque. Return true if the operation is successful. */
bool insertLast(int value) {
if(length==maxsize)
return false;
deque[prear]=value;
prear=(prear+1)%maxsize;
length++;
return true;
}
/** Deletes an item from the front of Deque. Return true if the operation is successful. */
bool deleteFront() {
if(length==0)
return false;
pfront=(pfront+1)%maxsize;
length--;
return true;
}
/** Deletes an item from the rear of Deque. Return true if the operation is successful. */
bool deleteLast() {
if(length==0)
return false;
prear=(prear-1+maxsize)%maxsize;
length--;
return true;
}
/** Get the front item from the deque. */
int getFront() {
if(length==0)
return -1;
return deque[pfront];
}
/** Get the last item from the deque. */
int getRear() {
if(length==0)
return -1;
return deque[(prear-1+maxsize)%maxsize];
}
/** Checks whether the circular deque is empty or not. */
bool isEmpty() {
return length==0;
}
/** Checks whether the circular deque is full or not. */
bool isFull() {
return length==maxsize;
}
};
来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/design-circular-deque
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