Remove Nth Node From End of List

Medium · Linked List

You are given the head of a singly linked list and an integer n. Remove the node that sits n positions from the end of the list and return the head of the resulting list. There is exactly one valid removal since n is guaranteed to be within range, so the goal is to find it without scanning the list twice.

Examples

Input:  head = [1,2,3,4,5], n = 2
Output: [1,2,3,5]
Why:    Counting from the end, the 2nd node is 4, so it is dropped from the chain.

Input:  head = [1], n = 1
Output: []
Why:    The only node is removed, leaving an empty list.

Input:  head = [1,2], n = 1
Output: [1]
Why:    The last node, 2, is removed leaving just 1.

Constraints

1 <= number of nodes <= 10^4, -10^5 <= node value <= 10^5, 1 <= n <= number of nodes

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This statement is written for CodeSpeek. The problem is part of the NeetCode 150 list; Watch NeetCode's explanation of Remove Nth Node From End of List. Reference solutions from the NeetCode repository (MIT) are used to verify our tests.