[Lintcode] #174 删除链表中倒数第n个节点

给定一个链表，删除链表中倒数第n个节点，返回链表的头节点。

/**
 * Definition for ListNode.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int val) {
 *         this.val = val;
 *         this.next = null;
 *     }
 * }
 */


public class Solution {
    /*
     * @param head: The first node of linked list.
     * @param n: An integer
     * @return: The head of linked list.
     */
    public ListNode removeNthFromEnd(ListNode head, int n) {
        // write your code here
        if (head == null)
			return null;
		ListNode newHead = new ListNode(-1);
		newHead.next = head;
		ListNode quicker = head;
		ListNode slower = newHead;
		while (n-- > 0)
			quicker = quicker.next;
		while (quicker != null) {
			slower = slower.next;
			quicker = quicker.next;
		}
		slower.next = slower.next.next;
		return newHead.next;
    }
}