[leedcode 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

/**
 * 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) {
        //需要构造安全头结点newhead，可以简化过程
        if(head==null) return head;
       
        ListNode newhead=new ListNode(-1);
        newhead.next=head;
        ListNode node=newhead;
        while(node.next!=null){
            if(node.next.val==val){
                node.next=node.next.next;
            }else{
                node=node.next;
            }
        }
        return newhead.next;
    }
}