一、移除链表元素
class Solution { public ListNode removeElements(ListNode head, int val) { if(head==null) return null; ListNode pre=head; ListNode cur=head.next; while(cur!=null){ if(cur.val==val){ pre.next=cur.next; cur=cur.next; } else{ pre=cur;; cur=cur.next; } } if(head.val==val){ head=head.next; } return head; } }
二、反转链表
class Solution { public ListNode reverseList(ListNode head) { if(head==null) return null; ListNode cur=head.next; head.next=null; while(cur!=null){ ListNode CUR=cur.next; cur.next=head; head=cur; cur=CUR; } return head; } }
三、找链表中间节点（一次循环）
class Solution { public ListNode middleNode(ListNode head) { if(head==null) return null; ListNode low=head; ListNode fast=head; while(fast!=null&&fast.next!=null){ low=low.next; fast=fast.next; fast=fast.next; } return low; } }
四、输入一个链表，输出该链表中倒数第k个结点
public class Solution { public ListNode FindKthToTail(ListNode head,int k) { if(k<=0||head==null){ return null; } ListNode low=head; ListNode fast=head; while(k-1!=0){ fast=fast.next; if(fast==null){ return null; } k--; } while(fast.next!=null){ low=low.next; fast=fast.next; } return low; } }
