删除链表的倒数第N个结点(leetcode19)

public class leetcode19 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        ListNode head = new ListNode(1);
        head.next = new ListNode(2);
        head.next.next = new ListNode(3);
        head.next.next.next = new ListNode(4);
        head.next.next.next.next = new ListNode(5);
        
        removeNthFromEnd(head,2);
        printNode(head);
    }
    //打印节点
    public static void printNode(ListNode head){
        while(head!=null){
            System.out.print(head.val+" ");
            head = head.next;
        }
    }

    //删除链表倒数第n个结点
    public static ListNode removeNthFromEnd(ListNode head, int n) {
        ListNode dummy = new ListNode(0,head);
        int length = getLength(head);
        ListNode cur = dummy;
        for(int i=1;i<length-n+1;i++){
            cur = cur.next;
        }
        cur.next = cur.next.next;
        ListNode ans = dummy.next;
        return ans;
    }
    //获取链表长度
    public static int getLength(ListNode head){
        int length=0;
        while(head!=null){
            ++length;
            head = head.next;
        }
        return length;
    }
}
//结点
class ListNode {
     int val;
     ListNode next;
     ListNode() {}
     ListNode(int val) { this.val = val; }
     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
}