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;
     }
 }