/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode removeNthFromEnd(ListNode head, int n) {
ListNode p=head;
int sum=0;
while(p!=null){
sum++;
p=p.next;
}
int m=sum-n;
if(m==0){
head=head.next;
return head;
}
p=head;
for(int i=0;i<m-1;i++){
p=p.next;
}
p.next=p.next.next;
return head;
}
}
Solution 2:追击办法 one pass
Follow up:Could you do this in one pass?
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode removeNthFromEnd(ListNode head, int n) {
ListNode fast=head;
ListNode curr=head;
for(int i=1;i<=n;i++){
fast=fast.next;
}
if(fast==null){
head=head.next;
return head;
}
while(fast.next!=null){
fast=fast.next;
curr=curr.next;
}
curr.next=curr.next.next;
return head;
}
}