链表的操作,防止日后遗忘

对于指针类型,他们拿的是a的地址,利用指针可以修改原来元素的值,如果有另一个指针q等于当前指针p,(注意是等于,不是指向),另一个指针q拿到的也是a的地址,此时将指针p设为null,对q无影响

*p++, *++p, ++,和 * 的 优先级相同,但是相同优先级从右向左执行
*p + 1先执行*运算

int a[2] = {1,12};
int *p;
p = &a[0];
int *q;
q = p;
p = NULL;
cout<<q[0];
//cout<<*++p<<endl;
//cout<<*p<<endl;

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution
{
    public:
        ListNode* merge(ListNode* l1, ListNode* l2)
        {
            ListNode *head,*cur;
            head = new ListNode(0);
            cur = head;
            while(l1 && l2)
            {
                if(l1 ->val < l2 ->val)
                {
                    head->next = l1;
                    head = head->next;
                    l1 = l1 ->next;
                }
                else
                {
                    head->next = l2;
                    head = head->next;
                    l2 = l2 ->next;
                }
            }
            if(l1)head->next = l1;
            if(l2)head->next = l2;
            return cur->next;
        }
};