leetcode 203. Remove Linked List Elements

Remove all elements from a linked list of integers that have value val.

Example:

Input: 1->2->6->3->4->5->6, val = 6 Output: 1->2->3->4->5 Accepted

增加头节点，以防止溢出

class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        ListNode *pseudo_head =new ListNode(0),*p;
        pseudo_head->next=head;
        p=pseudo_head;
        while(p){
           
            if(p->next && p->next->val==val) p->next=p->next->next; 
            //防止溢出的关键是先判断那个指针存在，再去用它的值
            else  p=p->next;
        }
        return pseudo_head->next;
    
    }
};