LintCode-452.删除链表中的元素

/**
 * 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) {
        // Write your code here
         if(head == null) return null;
        ListNode p = head,q = head.next;
        while(q != null){
            if(q.val == val){
                p.next = q.next;
                q = p.next;
            }
            else{
                p = p.next;
                q = q.next;
            }
        }
        if(head.val == val) head = head.next;
        return head;
    }
}