GuilinDev

Lc0237

05 August 2008

237 - Delete Note in a Linked List

原题概述

Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.

Given linked list – head = [4,5,1,9], which looks like following:

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    4 -> 5 -> 1 -> 9

Example 1:

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Input: head = [4,5,1,9], node = 5
Output: [4,1,9]
Explanation: You are given the second node with value 5, the linked list
             should become 4 -> 1 -> 9 after calling your function.

Example 2:

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Input: head = [4,5,1,9], node = 1
Output: [4,5,9]
Explanation: You are given the third node with value 1, the linked list
             should become 4 -> 5 -> 9 after calling your function.

Note:

  • The linked list will have at least two elements.
  • All of the nodes’ values will be unique.
  • The given node will not be the tail and it will always be a valid node of the linked list.
  • Do not return anything from your function.

题意和分析

这道题要删除链表的一个结点，但是并没有给链表的起点。正常的删除过程是把待删除的结点的前一个结点的next指向待删除节点的下一个结点。但这道题没有起点，不知道这个结点的上一个结点，所以做法是将这个结点的下一个结点的值复制到这个结点，然后删除下一个结点。

时间空间都是O(1)。

代码

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/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public void deleteNode(ListNode node) {
        node.val = node.next.val;
        node.next = node.next.next;
    }
}
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