19. Remove Nth Node From End of List

2019-03-29

19. Remove Nth Node From End of List

Given a linked list, remove the _n_-th node from the end of list and return its head.

Example:

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Given linked list: 1->2->3->4->5, and n = 2.

After removing the second node from the end, the linked list becomes 1->2->3->5.

Note:

Given _n_ will always be valid.

Follow up:

Could you do this in one pass?

Code:

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# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def removeNthFromEnd(self, head: ListNode, n: int) -> ListNode:
        self.next, nodelist  = head, [self]
        while head.next:
            if len(nodelist) == n:
                nodelist.pop(0)
            nodelist += head,
            head = head.next
        nodelist[0].next = nodelist[0].next.next
        return self.next
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