LeetCode:删除链表的倒数第N个节点(c#)

题目内容

代码实现

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     public int val;
 *     public ListNode next;
 *     public ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode RemoveNthFromEnd(ListNode head, int n) {
        //先跑N个位置的节点
        var fastNode = head;
        //先跑N位置
        for (int i = 0; i < n; i++)
            fastNode = fastNode.next;
        //如果快节点为null，说明删除的就是head节点
        if (fastNode == null)
            return head.next;
        //让快节点再跑一个节点
        fastNode = fastNode.next;
        //慢N+1位置节点，用于删除第N位置节点
        var slowNode = head;
        //循环往下追溯到尾部
        while (fastNode != null)
        {
            fastNode = fastNode.next;
            slowNode = slowNode.next;
        }
        //删除N号节点
        slowNode.next = slowNode.next.next;
        //返回头节点
        return head;
    }
}