题目描述
Design your implementation of the circular double-ended queue (deque).
Your implementation should support following operations:
MyCircularDeque(k): Constructor, set the size of the deque to be k.
insertFront(): Adds an item at the front of Deque. Return true if the operation is successful.
insertLast(): Adds an item at the rear of Deque. Return true if the operation is successful.
deleteFront(): Deletes an item from the front of Deque. Return true if the operation is successful.
deleteLast(): Deletes an item from the rear of Deque. Return true if the operation is successful.
getFront(): Gets the front item from the Deque. If the deque is empty, return -1.
getRear(): Gets the last item from Deque. If the deque is empty, return -1.
isEmpty(): Checks whether Deque is empty or not.
isFull(): Checks whether Deque is full or not.
Example:
MyCircularDeque circularDeque = new MycircularDeque(3); // set the size to be 3
circularDeque.insertLast(1); // return true
circularDeque.insertLast(2); // return true
circularDeque.insertFront(3); // return true
circularDeque.insertFront(4); // return false, the queue is full
circularDeque.getRear(); // return 32
circularDeque.isFull(); // return true
circularDeque.deleteLast(); // return true
circularDeque.insertFront(4); // return true
circularDeque.getFront(); // return 4
Note:
All values will be in the range of [1, 1000].
The number of operations will be in the range of [1, 1000].
Please do not use the built-in Deque library.
题目要求实现一个循环双端队列,我们可以使用std::list (std::list 底层是双向链表,std::forward_list是stl中的单向链表)实现,或者自己新建一个双向链表。
C++ 实现
class MyCircularDeque {
public:
/** Initialize your data structure here. Set the size of the deque to be k. */
MyCircularDeque(int k) {
upper_size = k;
}
/** Adds an item at the front of Deque. Return true if the operation is successful. */
bool insertFront(int value) {
if(deque.size() < upper_size)
{
deque.emplace_front(value);
return true;
}
return false;
}
/** Adds an item at the rear of Deque. Return true if the operation is successful. */
bool insertLast(int value) {
if (deque.size() < upper_size)
{
deque.emplace_back(value);
return true;
}
return false;
}
/** Deletes an item from the front of Deque. Return true if the operation is successful. */
bool deleteFront() {
if (!deque.empty())
{
deque.pop_front();
return true;
}
return false;
}
/** Deletes an item from the rear of Deque. Return true if the operation is successful. */
bool deleteLast() {
if (!deque.empty())
{
deque.pop_back();
return true;
}
return false;
}
/** Get the front item from the deque. */
int getFront() {
if (deque.empty())
{
return -1;
}
return deque.front();
}
/** Get the last item from the deque. */
int getRear() {
if (deque.empty())
{
return -1;
}
return deque.back();
}
/** Checks whether the circular deque is empty or not. */
bool isEmpty() {
return deque.empty();
}
/** Checks whether the circular deque is full or not. */
bool isFull() {
return deque.size() == upper_size;
}
private:
list<int> deque;
int upper_size;
};
/**
* 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();
*/