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  • 19. Remove Nth Node From End of List【Medium】【删除单链表倒数第n个结点】

    Given a linked list, remove the n-th node from the end of list and return its head.

    Example:

    Given linked list: 1->2->3->4->5, and n = 2.
    
    After removing the second node from the end, the linked list becomes 1->2->3->5.
    

    Note:

    Given n will always be valid.

    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) {
            if(head == null) return null;
            ListNode fast = head;
            while(n-- > 0) {
                fast = fast.next;
            }
            if(fast == null) return head.next;
            ListNode slow = head;
            while(fast.next != null) {
                slow = slow.next;
                fast = fast.next;
            }
            slow.next = slow.next.next;
            return head;
        }
    }

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  • 原文地址:https://www.cnblogs.com/Roni-i/p/10443907.html
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