Remove Nth Node From End of List

medium

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.

Input / output

Input: head: ListNode (JSON test fixture is a plain array of node values), n: int
Output: ListNode — the head of the list after removal (serialized the same way)

Constraints

The number of nodes in the list is between 1 and 30.
0 <= node value <= 100
1 <= n <= number of nodes (n is always valid, so the removed node always exists)

Can you do this in a single pass, without first counting the length of the list?

Examples

Example 1

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

Output: [1,2,3,5]

Example 2 (removing the only node)

Input: head = [1], n = 1

Output: []

Example 3 (removing the last node)

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

Output: [1]