leetcode：Remove Linked List Elements 【Java】

一、问题描述

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
二、问题分析

设置两个指针pre和cur。

三、算法代码

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