从Leetcode 每日一题练习继续讨论：
641. 设计循环双端队列
641. Design Circular Deque
题解
本题是中等难度题，但题目本身逻辑比较简单，要实现双端循环链表，只需记录下链表的首部和尾部位置信息，链表的当前大小和最大容量按要求实现即可。可以用数组也可以用链表，本题中我使用数组实现。
代码
class MyCircularDeque {
private:
vector<int> data;
int front;
int rear;
int size;
int capacity;
public:
MyCircularDeque(int k) : data(k), front(0), rear(0), size(0), capacity(k) {}
bool insertFront(int value) {
if (isFull()) return false;
data[front] = value;
if(size == 0){
rear = (front+1)%capacity;
}
front = (front - 1 + capacity) % capacity;
size++;
return true;
}
bool insertLast(int value) {
if (isFull()) return false;
data[rear] = value;
if (size == 0){
front = (rear - 1 + capacity) % capacity;
}
rear = (rear + 1) % capacity;
size++;
return true;
}
bool deleteFront() {
if (isEmpty()) return false;
front = (front + 1) % capacity;
size--;
return true;
}
bool deleteLast() {
if (isEmpty()) return false;
rear = (rear - 1 + capacity) % capacity;
size--;
return true;
}
int getFront() {
if (isEmpty()) return -1;
return data[(front+1)%capacity];
}
int getRear() {
if (isEmpty()) return -1;
return data[(rear - 1 + capacity) % capacity];
}
bool isEmpty() {
return size == 0;
}
bool isFull() {
return size == capacity;
}
};