203.移除链表元素

链接——链接

class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        if(!head)
        {
            return head;
        }
        //设置一个新的头结点指向head——就能解决
        ListNode* Newhead = new ListNode;
        Newhead->next = head;
        ListNode* tempnode = Newhead;

        while(tempnode->next)
        {
            if(tempnode->next->val == val)
            {
                ListNode* recv = tempnode->next;
                tempnode->next= tempnode->next->next;
                delete recv;  
            }
            else
            {
                tempnode = tempnode->next;
            }              
        }

        ListNode* temp = Newhead->next;
        delete Newhead;
        return temp;
    }
};

234.回文链表

题目——链接

class Solution {
public:
    bool isPalindrome(ListNode* head) {
        //用容器装，然后从头到后遍历比较
        //注意容器存储类型,存val内存开销会小一点
        vector<int>ListV;
        while(head)
        {
            ListV.push_back(head->val);
            head = head->next;
        }
        for(int i = 0,j= ListV.size()-1;i<j;i++,j--)
        {
                if(ListV[i]!= ListV[j])
                {
                    return false;
                }
        }
        return true;
    }
};

237.删除链表中的结点

题目——链接

//将变成后面的结点，然后将后面的结点删除防止内存泄漏
class Solution {
public:
    void deleteNode(ListNode* node) {
     ListNode* tempnode = node->next;
     node->val = tempnode->val;
     node->next = tempnode->next;
     delete tempnode;
    }
};