删除链表的倒数第 N 个结点

删除链表的倒数第 N 个结点

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    
    
    public ListNode removeNthFromEnd(ListNode head, int n) {
    
    
        ListNode dummy = new ListNode(-1);
        dummy.next = head;
        int N = 0;
        ListNode p = dummy;
        while (p != null) {
    
    
            N ++;
            p = p.next;
        }
        p = dummy;
        for (int i = 0; i < N - n - 1; i ++) {
    
    
            p = p.next;
        }
        
        p.next = p.next.next;
        return dummy.next;
    }
}