LeetCode（2） -- Remove Linked List Elements

链表 - Remove Linked List Elements

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Remove Linked List Elements

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

从一个链表中删除所有指定元素值的整数

ExampleGiven: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6Return: 1 --> 2 --> 3 --> 4 --> 5

思路：    需要保证头指针的准确，有可能前面连续三个 四个 都是指定要删除的数值，这个个数是不确定的

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算法：

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { val = x; } * } */class Solution {    public ListNode removeElements(ListNode head, int val) {                if(head == null){            return null;        }        //为了确保head的准确        while (head.val == val){            if(head.next != null){                head = head.next;            }else {                return null;            }        }        ListNode before = head;        if(head.next != null){            ListNode target = head.next;            while (target != null){                if(target.val == val){                    before.next = target.next;                    target = before.next;                }else {                    before = target;                    target = before.next;                }            }        }        return head;    }}