[Leetcode题目]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
题目翻译：

删除链表中值为指定值的节点

思路：链表基本功，注意头尾

1.比较节点值与val，并在循环中记录上一节点值，方便删除

/**
* 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){
if(head.val==val){
head=head.next;
}
else{
break;
}
}
if(head==null){
return null;
}
ListNode last=head;
ListNode node=head.next;
while(node!=null){
if(node.val==val){
node=node.next;
last.next=node;
}
else{
last=last.next;
node=node.next;
}
}
return head;
}
}

2. 直接比较下一节点的值与val，方便直接删除

/**
* Definition for singly-linked&nbs
3ff0
p;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){
if(head.val==val){
head=head.next;
}
else{
break;
}
}
if(head==null){
return null;
}
ListNode temp=head;
while(temp.next!=null){
if(temp.next.val==val){
temp.next=temp.next.next;
}
else{
temp=temp.next;
}
}
return head;
}
}