LeetCode--No.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.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
public class Solution {
public ListNode removeElements(ListNode head, int val) {
if (head == null)
return head;
ListNode first = new ListNode(0);
first.next = head;
ListNode prev = first;
while(head.next != null){
if (head.val != val){
prev = head;
head = head.next;
}
else{
head = head.next;
prev.next = head;
}
}
if (head.val == val)
prev.next = null;
return first.next;

}
}