19. Remove Nth Node From End of List

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?


Solution:

The question is not so hard. We just need to take care of some cases.

1. What if n == length of the given list?
2. If the length of LL is 1
3. What if the head is NULL.
4. General case if the Nth node is between the LL.

See the code below for better understanding.