标签:bsp fas list res int tno slow code 表操作
定义一个单链表
public class ListNode { int val; ListNode next; ListNode(int x) { val = x; } }
1.链表反转
思路:先将下一节点纪录下来,然后让当前节点指向上一节点,再将当前节点纪录下来,再让下一节点变为当前节点。
public class MainClass { public static void main(String[] args) throws IOException { ListNode a=new ListNode(1); a.next=new ListNode(2); a.next.next=new ListNode(3); ListNode cur=reserves(a); while(cur!=null){ System.out.println(cur.val); cur=cur.next; } } public static ListNode reserves(ListNode a){ ListNode pre=null; ListNode cur=a; while(cur!=null){ ListNode next=cur.next; cur.next=pre; pre=cur; cur=next; } return pre; } }
2.删除链表某个节点
前提:链表中值都是唯一的
public class MainClass { public static void main(String[] args) throws IOException { ListNode a=new ListNode(1); ListNode b=new ListNode(4); a.next=b; a.next.next=new ListNode(3); a.next.next.next=new ListNode(6); ListNode cur=deleteNode(a,b); while(cur!=null){ System.out.println(cur.val); cur=cur.next; } } public static ListNode deleteNode(ListNode a,ListNode b){ if(b.next==null){ while(a.next!=b){ a=a.next; } a.next=null; }else if(a==b){ a=null; }else{ b.val=b.next.val; b.next=b.next.next; } return a; } }
3.判断链表是否有环
public class MainClass { public static void main(String[] args) throws IOException { ListNode a=new ListNode(1); ListNode b=new ListNode(4); a.next=b; a.next.next=new ListNode(3); a.next.next.next=new ListNode(6); //a.next.next.next.next=b; boolean flag=isRing(a); System.out.println(flag); } public static boolean isRing(ListNode head){ if(head==null) return false; ListNode fast=head; ListNode slow=head; while(fast!=null&&fast.next!=null){ slow=slow.next; fast=fast.next.next; if(slow==fast){ return true; } } return false; } }
4.倒数K个节点
public class MainClass { public static void main(String[] args) throws IOException { ListNode a=new ListNode(1); ListNode b=new ListNode(4); a.next=b; a.next.next=new ListNode(3); a.next.next.next=new ListNode(6); a.next.next.next.next=new ListNode(7);; ListNode k=getReverNode(a,5); System.out.println(k.val); } public static ListNode getReverNode(ListNode head,int k){ if(head==null ){ return null; } ListNode fast=head; for(int i=0;i<k-1;i++){ fast=fast.next; } ListNode slow=head; while(fast.next!=null){ fast=fast.next; slow=slow.next; } return slow; } }
标签:bsp fas list res int tno slow code 表操作
原文地址:https://www.cnblogs.com/hanxiaomin/p/11420583.html