卖萌的弱渣

I am stupid, I am hungry.

Remove Nth Node From End of List

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

For 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.

  • Try to do this in one pass.

Solution

(Remove-Nth-Node-from-End-of-List.py) download
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# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def removeNthFromEnd(self, head, n):
        """
        :type head: ListNode
        :type n: int
        :rtype: ListNode
        """
        newHead = ListNode(-1)
        newHead.next = head

        # get length
        length = 0
        while head != None:
            head=head.next
            length += 1

        head = newHead
        i = 0
        while i < length-n:
            i += 1
            head = head.next

        head.next = head.next.next
        return newHead.next