[2095] Delete the Middle Node of a Linked List | Python

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문제 링크: https://leetcode.com/problems/delete-the-middle-node-of-a-linked-list/

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문제

You are given the head of a linked list. Delete the middle node, and return the head of the modified linked list.

The middle node of a linked list of size n is the ⌊n / 2⌋th node from the start using 0-based indexing, where ⌊x⌋ denotes the largest integer less than or equal to x.

• For n = 1, 2, 3, 4, and 5, the middle nodes are 0, 1, 1, 2, and 2, respectively.

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조건

• The number of nodes in the list is in the range [$1, 10^5$].
• 1 <= Node.val <= $10^5$

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내 풀이

list를 앞부터 뒤까지 쭉 훑으며 list의 길이를 잰다.

list 길이의 절반이 되는 지점을 없앤다.

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코드

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def deleteMiddle(self, head: Optional[ListNode]) -> Optional[ListNode]:
        length = 1
        nhead = head
        
        while nhead.next:
            length += 1
            nhead = nhead.next
        
        if length == 1:
            return None
        elif length == 2:
            head.next = None
        
        nhead = head
        half = 1
        while nhead.next:
            half += 1
            if half == length//2+1:
                nhead.next = nhead.next.next
                break
            nhead = nhead.next
            
        return head​