203. Remove Linked List Elements

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

Credits:

Special thanks to
@mithmatt for adding this problem and creating all test cases.

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/**
* 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) {
ListNode* temp=head;
ListNode* pre=NULL;
while(head)
{
if(head->val==val)
{
if(pre!=NULL)
{
pre->next=head->next;
}
else
{
temp=head->next;
}

}
else
{
pre=head;
}

head=head->next;
}
return temp;
}
};