设计链表

class MyLinkedList {
public:
    MyLinkedList() {                    //  设置虚拟头结点会好做很多
        list=new myLinkedList(0);
    }
    
    int get(int index) {
        myLinkedList* cur=list->next;
        int i=0;
        while(cur!=NULL){
            if(i==index){
                i=cur->val;
                return i;
            }
            i++;
            cur=cur->next;
        }
        return -1;
    }
    
    void addAtHead(int val) {
        myLinkedList* cur=new myLinkedList(val);
        cur->next=list->next;
        list->next=cur;
    }
    
    void addAtTail(int val) {
        myLinkedList *cur=list;
        while(cur->next!=NULL){
            cur=cur->next;
        }
        cur->next=new myLinkedList(val);
    }
    
    void addAtIndex(int index, int val) {
        myLinkedList *cur=new myLinkedList(0);
        cur=list;
        int i=0;
        while(cur->next!=NULL){
            if(i==index){
                myLinkedList* tmp=new myLinkedList(val);
                tmp->next=cur->next;
                cur->next=tmp;
            }
            i++;
            cur=cur->next;
        }
        if(cur->next==NULL&&i==index){
            cur->next=new myLinkedList(val);
        }
    }
    
    void deleteAtIndex(int index) {
        myLinkedList *cur=new myLinkedList(0);
        cur->next=list->next;
        list=cur;
        int i=0;
        while(cur->next!=NULL){
            if(i==index){
                cur->next=cur->next->next;
                break;
            }
            i++;
            cur=cur->next;
        }
    }
private:
    struct myLinkedList{
        int val;
        myLinkedList* next;
        myLinkedList(int x) : val(x), next(NULL) {}
    };
    myLinkedList* list;
};

/**
 * Your MyLinkedList object will be instantiated and called as such:
 * MyLinkedList* obj = new MyLinkedList();
 * int param_1 = obj->get(index);
 * obj->addAtHead(val);
 * obj->addAtTail(val);
 * obj->addAtIndex(index,val);
 * obj->deleteAtIndex(index);
 */