Remove Nth Node From End of List . dEexams.com

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:

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def removeNthFromEnd(self, head: Optional[ListNode], n: int) -> Optional[ListNode]:
        dummy = ListNode(0, head)
        L, R = dummy, head
        c = 0
        while n > 0 and R:
            R = R.next
            n -= 1
        while R:
            L = L.next
            R = R.next
        
        L.next = L.next.next
        return dummy.next

Uk01 on Jan 29, 2022 at 10:01 am

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