19. 删除链表的倒数第 N 个结点

Description #

Difficulty: 中等

Related Topics: Linked List, Two Pointers

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

Example 1:

Input: head = [1,2,3,4,5], n = 2
Output: [1,2,3,5]

Example 2:

Input: head = [1], n = 1
Output: []

Example 3:

Input: head = [1,2], n = 1
Output: [1]

Constraints:

• The number of nodes in the list is sz.
• 1 <= sz <= 30
• 0 <= Node.val <= 100
• 1 <= n <= sz

Follow up: Could you do this in one pass?

Solution #

Language: Go

空间替换时间：使用 map 记录“链”。key 为链表的序号，value 记录 next。删除倒数 n 个数字时，只需要将 n-1 的 value 指向 n+1 即可。

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