LeetCode OJ ：Remove Linked List Elements (移除链表元素)

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

ps：这一题感觉没什么技巧可言，选取一个头指针，一个当前指针，一个前向指针。简单的链表操作而已，代码如下：

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* removeElements(ListNode* head, int val) {
        ListNode * root = head;
        ListNode * prev = head;
        ListNode * curr = head;
        while (curr != NULL){
            if (curr->val == val){
                if (prev == curr)
                    root = prev = curr = curr->next;
                else{
                    curr = curr->next;
                    prev->next = curr;
                }
            }else{
                prev = curr;
                curr = curr->next;
            }
        }
        return root;
    }
};

 java版本如下所示：

/**
 * 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) {
        while(head != null && head.val == val){
            ListNode helper = head;
            head = head.next;
            helper.next = null;
        }
        if(head == null)
            return head;
        ListNode p1 = head;
        while(p1.next != null){
            if(p1.next.val == val){
                p1.next = p1.next.next;
            }else
                p1 = p1.next;
        }
        return head;
    }
}