LeetCode（203）——Remove Linked List Elements

题目：

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

AC:

class Solution {
    public ListNode removeElements(ListNode head, int val) {
        if (null == head) {
            return head;
        }
        
        ListNode dummyNode = new ListNode(-1);
        ListNode currNode = head;
        ListNode prevNode = dummyNode;
        dummyNode.next = head;
        
        while (null != currNode) {
            if (val == currNode.val) {
                prevNode.next = currNode.next;
                currNode = currNode.next;
            }
            else {
                prevNode = prevNode.next;
                currNode = currNode.next; 
            }
        }
        
        return dummyNode.next;
    }
}