［Lintcode］ Remove Linked List Elements 删除連結清單中的元素

删除連結清單中等于給定值val的所有節點。

樣例

給對外連結表 1->2->3->3->4->5->3, 和 val = 3, 你需要傳回删除3之後的連結清單：1->2->4->5。

Remove all elements from a linked list of integers that have value val.

Example

Given 1->2->3->3->4->5->3, val = 3, you should return the list as 1->2->4->5

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    /**
     * @param head a ListNode
     * @param val an integer
     * @return a ListNode
     */
    public ListNode removeElements(ListNode head, int val) {
        if(head == null) return head;
        ListNode p = head, q = head.next;
        while(q != null) {
            if(q.val == val) {
                p.next = q.next;
                q = q.next;
            }else{
                p = p.next;
                q = q.next;
            }
        }
        if(head.val == val) head = head.next;
        return head;
    }
}