0019: Remove Nth Node From End of List

Problem Statement

Given the head of a linked list, remove the nth 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?

Code Solution

class Solution:
    def removeNthFromEnd(self, head, n):
        temp = head
        for ix in range(n):
            temp = temp.next
        
        if not temp:
            return head.next
        
        curr = head
        while temp and temp.next:
            curr = curr.next
            temp = temp.next
        
        curr.next = curr.next.next
        return head