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.

Follow up: Could you do this in one pass?

 

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

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution(object):
    def removeNthFromEnd(self, head, n):
        """
        :type head: ListNode
        :type n: int
        :rtype: ListNode
        """
        
        l = 0
        cur = head
        while cur:
            cur = cur.next
            l +=1

        target = l - n
        l = 0
        
        if target == 0:
            return head.next
        
        cur = head
        
        while cur:
            if l == target-1:
                cur.next = cur.next.next
            cur = cur.next
            l+=1
        return head
        

- 두 번 선회하다보니 느릴줄 알았는데, 16 ms, faster than 91.44% of Python 가 나왔다.