LeetCode-641. 设计循环双端队列

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。

基础题，注意边界值，双向链表，一个头节点，一个尾节点

#include <iostream>

using namespace std;

class MyCircularDeque {

private:
    struct node{
        int val;
        struct node* next;
        struct node* pre;
        node(int x):val(x),next(NULL),pre(NULL){}
    };
    int now_cap;
    int total_cap;
    node* head;
    node* tail;

public:
    /** Initialize your data structure here. Set the size of the deque to be k. */
    MyCircularDeque(int k) {
        now_cap = 0;
        total_cap = k;
        head = new node(0);
        tail = new node(0);
        head->next = tail;
        tail->pre = head;
    }

    /** Adds an item at the front of Deque. Return true if the operation is successful. */
    bool insertFront(int value) {
        if(now_cap<total_cap){
            now_cap++;
            node* insert = new node(value);
            if(head->next!=NULL){
                node* first = head->next;
                head->next = insert;
                insert->pre = head;
                insert->next = first;
                first->pre = insert;
            }else{
                head->next =insert;
                insert->pre = head;
            }
            return true;
        }else{
            return false;
        }
    }

    /** Adds an item at the rear of Deque. Return true if the operation is successful. */
    bool insertLast(int value) {
        if(now_cap<total_cap){
            now_cap++;
            node* insert = new node(value);
            node* pre = tail->pre;
            pre->next =insert;
            insert->pre = pre;
            insert->next = tail;
            tail->pre  = insert;

            return true;
        }else{
            return false;
        }
    }

    /** Deletes an item from the front of Deque. Return true if the operation is successful. */
    bool deleteFront() {
        if(now_cap<=0)
            return false;

        if(head->next==NULL)
            return false;
        else{
            now_cap--;
            node* first =head->next;
            node* second = first->next;

            first->next =NULL;
            first->pre = NULL;

            if(second==NULL){
                head->next = NULL;
            }else{
                head->next = second;
                second->pre = head;
            }
            delete(first);
            return true;
        }
    }

    /** Deletes an item from the rear of Deque. Return true if the operation is successful. */
    bool deleteLast() {
        if(now_cap<=0)
            return false;
        node *last =tail->pre;
        node *pre = last->pre;
        pre->next = tail;
        tail->pre = pre;
        last->next = NULL;
        last->pre  =NULL;
        now_cap--;

        delete(last);

        return true;

    }

    /** Get the front item from the deque. */
    int getFront() {
        if(head->next!=tail){
            return head->next->val;
        }else{
            return -1;
        }
    }

    /** Get the last item from the deque. */
    int getRear() {
        if(tail->pre!=head){
            return tail->pre->val;
        }else{
            return -1;
        }
    }

    /** Checks whether the circular deque is empty or not. */
    bool isEmpty() {
        if(now_cap==0)
            return true;
        else
            return false;
    }

    /** Checks whether the circular deque is full or not. */
    bool isFull() {
        if(now_cap==total_cap)
            return true;
        else
            return false;
    }

    //    void print(){
    //        while(head->next!=NULL){
    //            cout<<"test:"<<head->next->val<<endl;
    //            head =head->next;
    //        }
    //    }
};

int main(){

    //    MyCircularDeque* obj = new MyCircularDeque(3);
    //    cout<<obj->insertLast(1)<<endl;
    //    cout<<obj->insertLast(2)<<endl;
    //    cout<<obj->insertFront(3)<<endl;
    //    cout<<obj->insertFront(4)<<endl;
    //    cout<<obj->getRear()<<endl;
    //    cout<<obj->isFull()<<endl;
    //    cout<<obj->deleteLast()<<endl;
    //    cout<<obj->insertFront(4)<<endl;
    //    cout<<obj->getFront()<<endl;


    MyCircularDeque* obj = new MyCircularDeque(4);
    cout<<obj->insertFront(9)<<endl;
    cout<<obj->deleteLast()<<endl;
    cout<<obj->getRear()<<endl;
    cout<<obj->getFront()<<endl;
    cout<<obj->getFront()<<endl;
    cout<<obj->deleteFront()<<endl;

    //    cout<<obj->insertFront(3)<<endl;
    //    cout<<obj->insertFront(4)<<endl;
    //    cout<<obj->isFull()<<endl;
    //    cout<<obj->deleteLast()<<endl;
    //    cout<<obj->insertFront(4)<<endl;
    //    cout<<obj->getFront()<<endl;


    return 0;
}