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237. Delete Node in a Linked List

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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Example 1:

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:

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.

思路分析

这个题其实很简单!把节点的值覆盖当前节点的值即可。

没想到打脸如此之快!还有更简单的办法,两行代码搞定:①把下一个节点的值拷贝到当前节点;②把当前节点的下一节点指向下下一个节点即可。

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/**
 * Runtime: 0 ms, faster than 100.00% of Java online submissions for Delete Node in a Linked List.
 *
 * Memory Usage: 36.2 MB, less than 100.00% of Java online submissions for Delete Node in a Linked List.
 *
 * Copy from: https://leetcode.com/problems/delete-node-in-a-linked-list/solution/[Delete Node in a Linked List solution - LeetCode]
 *
 * @author D瓜哥 · https://www.diguage.com
 * @since 2020-01-13 20:28
 */
public void deleteNode(ListNode node) {
    node.val = node.next.val;
    node.next = node.next.next;
}

/**
 * Runtime: 0 ms, faster than 100.00% of Java online submissions for Delete Node in a Linked List.
 *
 * Memory Usage: 36.5 MB, less than 100.00% of Java online submissions for Delete Node in a Linked List.
 */
public void deleteNodeCopyList(ListNode node) {
    ListNode current = node;
    while (Objects.nonNull(current) && Objects.nonNull(current.next)) {
        ListNode next = current.next;
        current.val = next.val;
        if (Objects.nonNull(next.next)) {
            current = next;
        } else {
            current.next = null;
        }
    }
}
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/**
 * @author D瓜哥 · https://www.diguage.com
 * @since 2024-09-16 20:54:33
 */
public void deleteNode(ListNode node) {
  // 把后面一个元素拷贝过来
  node.val = node.next.val;
  // 把当前元素的下节点指针指向下下节点
  node.next = node.next.next;
}