[LeetCode]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

Credits:
Special thanks to @mithmatt for adding this problem and creating all test cases.

 

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指定2个指针，cur  pre;

当cur！=null ,repeat:

　　当cur.val==val 时，pre.next  指向 cur.next;

　　当cur.val != val 时，pre = pre.next;(pre 向后移动)

　　cur 向后移动

 

public class Solution {
    public ListNode removeElements(ListNode head, int val) {
   ListNode head_pre = new ListNode(-1);
        head_pre.next = head;
        ListNode  pre = head_pre;
        ListNode  cur = head;
        while(cur != null){
            if(cur.val == val)
                pre.next = cur.next;
            else
                pre = pre.next;
            cur = cur.next;
        }
        return head_pre.next;

    }

}