Remove all elements from a linked list of integers that have value val.
Example
Given: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6
Return: 1 --> 2 --> 3 --> 4 --> 5
Example
Given: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6
Return: 1 --> 2 --> 3 --> 4 --> 5
思路:在一个链表中,移除等于给定数值的链表节点。使用一个辅助头节点进行帮忙,记录每个节点的前驱节点,如果当前节点的val值等于给定的val值,则当前节点是需要移除的节点。由于在整个遍历过程中已经记录了当前节点的前驱节点,移除操作就比较简单了。
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* removeElements(ListNode* head, int val) {
if(head==NULL)
return head;
ListNode *res=new ListNode(0),*pre=res;
res->next=head;
ListNode *p=head;
while(p)
{
if(p->val==val)
{
ListNode *tmp=p->next;
pre->next=tmp;
delete p;
p=tmp;
}
else
{
pre=p;
p=p->next;
}
}
return res->next;
}
};